The Manchester Gorton by-election will be held on 4 May, the Labour Party has confirmed.

The seat has been left vacant following the death of long-serving Labour MP Sir Gerald Kaufman in February.
Labour, who chose North West MEP Afzal Khan to stand in the by-election, are being challenged by the former Labour and Respect MP George Galloway.
Voting will take place on the same day as the Greater Manchester mayoral elections.
Labour's chief whip Nicholas Brown moved a writ in the House of Commons on Tuesday to trigger the by-election which was then approved by MPs.
Lisa Nandy, who is coordinating Labour's campaign, told a meeting of the party's MPs at Westminster on Monday that they were "confident but not complacent" about holding Gorton.
Manchester Gorton has been a Labour seat since 1935. Sir Gerald held it with a majority of 24,079 at the 2015 general election, winning 67% of the total vote.
Sir Gerald, who was the longest-serving MP in Westminster, died aged 86 after serving the constituency for over 30 years.
The Green Party has chosen 36-year-old entrepreneur Jess Mayo as their candidate.
The Lib Dems, who came fifth last time, have selected Jackie Pearcey.
The Conservatives and UKIP, who came third and fourth respectively in 2015, are yet to announce their candidates.
George Galloway announced last week he would stand as an independent candidate.


Part-time Braintree Town secured a National League play-off place by beating Altrincham, whose relegation was confirmed by defeat in Essex.

Grimsby and Dover both lost their final games, meaning Braintree finished third and will have a home second leg in their semi-final against Grimsby.
Striker Michael Cheek netted twice for the hosts before half-time and Mitch Brundle added a third from close range.
Altrincham needed to win to stand any chance of survival.
A 5-0 home win over Welling in their previous outing, which ended a seven-match winless run, gave them hope of an unlikely escape but Alty will return to the sixth tier of English football next season after two years in the National League.
Braintree, who are managed by PE teacher Danny Cowley, are aiming to reach the Football League for the first time in their history.


A Lebanese TV journalist and her station have been cleared of obstructing justice by a UN-backed tribunal investigating the 2005 killing of former Prime Minister Rafik Hariri.

Karma Khayat and Al Jadeed had been accused of having revealed details about key protected witnesses.
But Ms Khayat was convicted of contempt of court for failing to remove broadcasts about the case online.
Five men accused of the killing are being tried in absentia.
Mr Hariri died along with 21 others when his motorcade was hit by a massive bomb blast in the Lebanese capital Beirut on 14 February 2005.
The Special Tribunal for Lebanon (STL) was set up by the United Nations to try those accused in connection with the killings.
The five suspects still at large have been linked to the militant Shia Islamist movement, Hezbollah.
Ms Khayat was the first defendant to take the stand at the STL.
Prosecutors alleged the journalist and Al Jadeed had deliberately set out to reveal the identities of witnesses who had been promised anonymity.
Ms Khayat said the list of names she published was redacted, which made it impossible to identify any witnesses.
She said her reports had exposed alleged leaks coming from the tribunal and accused the court of attempting to silence criticism of it.
Although Ms Khayat was cleared of the main charge, the judge said she had committed contempt of court for ignoring a ruling ordering the removal online of 2012 broadcasts to do with the case.
She will be sentenced later this month.


Pub company Punch Taverns is to sell 158 mostly "non-core" pubs for £53.5m to New River Retail, an investment trust focused on the UK retail sector.

The deal is expected to be completed on 11 September.  Proceeds from the cash sale will be used to reduce net debt.
The move is part of Burton-based Punch's strategy to sell its non-core pubs at a rate of about 200 a year.
Punch boss Duncan Garrood said the sale would allow it to focus "on our higher quality core pub estate".
The disposal comprises 150 pubs from the non-core estate and eight pubs from the core estate that "no longer meet our criteria as a core pub".
The pubs being sold generated earnings before interest and tax of £7.3m over the past 12 months, and have a current book value of £52.5m, Punch added.
After the sale, the company's core estate will have about 2,900 pubs and the non-core estate will have about 550 pubs.
Punch will issue a full-year trading update for the financial year to 22 August on 1 September.


The Iraq Inquiry says it cannot proceed with the next phase of its work because key information, including correspondence between Tony Blair and George W Bush, has yet to be released.

The inquiry chaired by Sir John Chilcot had hoped to begin contacting those likely to be criticised in its report this autumn, to allow them to respond.
But it said it had not yet agreed with the government over the publication of the most "difficult documents".
The inquiry began its work in 2009.
In a statement on the inquiry's website, Sir John said the next phase of its work was "dependent on the satisfactory completion of discussions between the inquiry and the government on disclosure of material that the inquiry wishes to include in its report or publish alongside it".
He added: "Since June this year the inquiry has submitted 10 requests covering some 200 cabinet-level discussions, 25 notes from Mr Blair to President Bush and more than 130 records of conversations between either Mr Blair or Mr [Gordon] Brown and President Bush.
"The inquiry secretariat has responded to a number of Cabinet Office questions on those requests, but the government and the inquiry have not reached a final position on the disclosure of these more difficult categories of document."
Sir John has written to Prime Minister David Cameron to express his regret that no agreement has yet been reached.
In his reply, the prime minister acknowledged the progress that had been made and said he was "aware of the scale of the task declassification has presented to a number of government departments".
He added: "I appreciate consideration of the disclosure requests for the remaining sensitive categories of information must be handled sensitively and carefully but I hope that consideration of the final sets of papers can be concluded as soon as possible."
A spokeswoman for No 10 said she had nothing to add to the prime minister's letter. The Cabinet Office has released a statement saying "discussions are continuing between the government and the inquiry about the disclosure of records".
BBC political correspondent Carole Walker said this was the latest in a series of delays to the long-running inquiry.
The inquiry, which is examining the background to the UK's involvement in the 2003 invasion and its aftermath, has never set a firm deadline for publishing its final report - set to be about a million words long.
However, it was initially expected to be published in 2012.


Richard Gray was rarely happier than when playing hockey for the club he founded, watched by his family.

The Ipswich & East Suffolk Hockey Club was a passion for the father-of-two ever since he helped set it up in 1986.
And as his children, Adam and Ruby, grew up they often watched him play.
Mr Gray was on his way to work as a tax manager with chartered accountants FW Smith Riches when he was killed at Aldgate.
He was blown out of the Tube carriage by the force of the blast and his body was found on the tracks outside.
Mr Gray and his wife Louise met when she was just 15 at the hotel where she had a part-time job serving breakfasts. They moved in together the following year and were married on 30 March 1991.
In her police statement, read to the inquest, Mrs Gray said there was nothing out of the ordinary about her husband's routine on 7 July 2005.
He got up at 6.00am, as he always did, before watching the news on television for an hour. He left home at 7.15am, dressed for work and carrying his briefcase.
That was the last time Mrs Gray saw her husband alive.
She described him as "fun-loving, kind and generous, an ordinary family man".
The image of him as a devoted husband and father was echoed by a fellow hockey player at his club.
"Richard was a gentleman of modest disposition, charm, courtesy and subtle humour and above all he was a family man."
As a member of the club's 3rd or 4th XI teams, he was also regarded as a pacy midfield or forward with an eye for goal.
Mr Gray had worked for FW Smith Riches for about five years and after his death the company said in a statement: "He was both well-liked and well thought of by partners and staff alike.
"Hard-working, conscientious and always ready to stop whatever he was doing and help out.
"Richard has always made a lot of time for the clients, happy to talk to them about all sorts of concerns as well as their financial offers."
Many of Mr Gray's clients had contacted the company to express their sympathy, the statement added.


Dumfries and Galloway Arts Festival has launched the programme for this year's event which it says is its "most ambitious to date".

Singer and songwriter Karine Polwart kicks off proceedings at the Easterbrook Hall in Dumfries on 26 May.
A wide range of theatre, music and comedy performances will follow throughout the region.
Billed as Scotland's largest rural performing arts festival, it runs until 4 June.
Among the events being highlighted by organisers are:
Ken Gouge, who chairs the festival, said the event had been going from strength to strength.
"We're anticipating our audience figures increasing again," he said.
"In the last two years we have more than doubled our audience figures and, indeed, our ticket income has gone up by 131% over the last two years.
"So we are clearly doing something right."
The full programme is available on the arts festival's website.


The International Criminal Court has found Congo militia leader Germain Katanga guilty of war crimes but acquitted him of sexual offences.

He was found guilty of complicity in the 2003 massacre of villagers in the gold-rich Ituri province of north-eastern Democratic Republic of Congo.
He becomes just the second person to be convicted by the court since it was set up in The Hague in 2002.
He would have been the first convicted of sexual crimes.
Katanga, who was transferred to The Hague by the Congolese authorities in 2007, had denied the charges.
The fighting in Ituri, which broke out in 1999 and continued until 2003, started as a struggle for control of land and resources.
But it escalated into an inter-ethnic conflict, exacerbated by the presence of Uganda troops, that killed an estimated 50,000 people.
Q&A: International Criminal Court
Will Africa pull out of the ICC?
Will trials bring peace to Ituri?
Katanga was convicted of being an accessory to an attack on Bogoro that took place on 24 February 2003, killing more than 200 people.
In a majority verdict, the judges said he had helped plan the attack, and procure the weapons used, but they acquitted him of direct involvement.
He was also cleared of using child soldiers.
In total, he was convicted of being an accessory to four counts of war crimes and one crime against humanity.
He will be sentenced at a future hearing.
ICC prosecutors at The Hague say the assault was designed to "wipe out" the entire strategically important village, which is close to the Ugandan border.
According to the prosecution, the attack happened early in the morning and some villagers were shot while they slept, while others were cut up with machetes to save bullets.
Without the "supply of weapons... commanders would not have been able to carry out the attack with such efficiency," said presiding judge Bruno Cotte.
At the time Katanga was 24 years old and the alleged commander of the Patriotic Resistance Force of Ituri (FRPI), which had the support of the Lendu ethnic group.
The prosecution said that as the FRPI's leader, he was to blame for the atrocities committed by his fighters against the villagers from the Hema ethnic group.
The judges found that women who survived the massacre had been raped or kept as sex slaves but they did not find enough evidence to convict Katanga of carrying out these crimes.
Another person was charged by the ICC in connection with the Bogoro attack.
But in December 2012 Mathieu Ngudjolo Chui was acquitted as judges found there was insufficient evidence to show that he was the commander of National Integrationist Front (FNI), which also took part in the raid.
The BBC's Maud Jullien in DR Congo says Katanga was known to his men as "Simba", meaning lion.
Those who knew him describe him as a discreet man but ruthless on the battlefield, she says.
After the end of the Ituri conflict, peace deals were signed and Katanga was given a position in the Congolese army.
But a year after joining the military he was imprisoned for bad behaviour and was still in prison when the ICC issued its arrest warrant for him.
His is one of the longest-running cases at the ICC.
In July 2012, Thomas Lubanga, a rival militia leader in Ituri, was sentenced to 14 years in jail by the ICC for recruiting and using child soldiers.


Kimi Raikkonen finished pre-season testing in Barcelona fastest as Ferrari gave notice they could be a genuine threat at the first race in Australia on 26 March.

The Finn's lap of 1:18.634 was 0.39secs quicker than the previous best by team-mate Sebastian Vettel and is 0.686secs faster than anything by Mercedes.
Lewis Hamilton was fifth fastest, 1.216secs slower than Raikkonen.
McLaren-Honda's dismal winter continued with two on-track stoppages.
They also endured another day of very limited mileage as Fernando Alonso suffered the same intermittent electrical problem that had caused two on-track stoppages for team-mate Stoffel Vandoorne on Thursday.
The Spaniard ended the day with the team's fastest time of the winter - but he was still only 11th fastest and 2.755secs off the pace.
And for the third day in a row they failed to complete even 50 laps - the only team in that position.
Raikkonen's time was all the more impressive for being set on super-soft tyres - Vettel had used the theoretically faster ultra-softs to set his best time on Thursday.
The 2007 world champion, who had a spin in the afternoon that disrupted a race-simulation run, did also use the ultra-softs but was 0.3secs slower than his best lap.
Red Bull also showed some strong pace with Max Verstappen second-fastest on a 1:19.438, 0.4secs ahead of Mercedes' Valtteri Bottas.
Pre-season testing times are notoriously unreliable indicators of true form because there are so many possible variables in the specification of the cars.
But the growing feeling within F1 is that Ferrari may start the season with a genuinely competitive car.
"The others look very quick and it looks like we have a good battle on our hands," said Hamilton.
"Ferrari have done a fantastic job and I think there's more to come from them. Their pace has really been spectacular.
"I don't know if Red Bull have brought their upgrade package here but normally they bring it to the first race. They're definitely still up there. I expect us to be having a real serious battle with both these teams.
"I don't know if we can go as fast as them, I really don't. We'll find out. We hope we can, but they've done a fantastic job."
Fastest times, day four, final pre-season test
1 Kimi Raikkonen (Fin) Ferrari 1:18.634 **
2 Max Verstappen (Ned) Red Bull 1:19.438 **
3 Carlos Sainz (Spa) Toro Rosso 1:19.837 ***
4 Valtteri Bottas (Fin) Mercedes 1:19.845 **
5 Lewis Hamilton (GB) Mercedes 1:19.850 ***
6 Nico Hulkenberg (Ger) Renault 1:19.885 ***
7 Sergio Perez (Mex) Force India 1:20.116 ***
8 Jolyon Palmer (GB) Renault 1:20.205 ***
9 Lance Stroll (Can) Williams 1:20.335 *
10 Romain Grosjean (Fra) Haas 1:21.110 ***
11 Fernando Alonso (Spa) McLaren 1:21.389 ***
12 Marcus Ericsson (Swe) Sauber 1:21.670 **
13 Pascal Wehrlein (Ger) Sauber 1:23.527 *
*** = ultra-soft tyre; ** = super-soft; * = soft


Smoke from huge forest fires in Indonesian has created a cloud of smog over the country, which has spread over neighbouring Malaysia and Singapore.

The fires, which happen every year, are caused by slash-and-burn clearances on the islands of Sumatra and Borneo.
Paper and palm oil companies have been widely blamed for the practice.
Indonesia, which has repeatedly promised to stop the illegal fires, has sent hundreds of military personnel to try to put them out.
It has declared a state of emergency in Riau province, where the haze has been building for several weeks and pollution levels are hazardous to health.
In Malaysia, schools have been closed in the capital, Kuala Lumpur, and several other areas, while Singaporeans are being advised to avoid strenuous activity outdoors.


Newport Gwent Dragons captain Lewis Evans says their players are uncertain about the future of the region.

The Welsh Rugby Union (WRU) are set to take over the Dragons as well as their Rodney Parade ground, but the deal will not be completed until 1 July.
75% of Newport RFC shareholders must still ratify the deal which chairman Martyn Hazell called for them to back.
"Until something gets sorted above, we've got to get on with our jobs," Evans told BBC Radio Wales.
He continued: "The future for Dragons rugby is positive and as players we've got to make sure it happens on the field and whatever goes on off the field is down to the bigwigs.
"Whatever goes on at the top, hopefully it moves in the right direction and we get a positive future."
Evans made his 200th appearance for the region in their 17-27 Pro12 defeat by Ulster and is proud of his record.
"They all merge into one and it's something I'm proud of. Running out [against Ulster] was really emotional," he said.
"It's nice to be able to come out in the last game of the season at Rodney Parade which I was really looking forward to.
"I felt good going into this game and unfortunately it didn't quite go our way and I thought the performance was there.
"We want to play attacking and attractive rugby and get some wins."


A man charged with the murder of a grandfather who was attacked as he walked his dogs has appeared in court.

Alexander Palmer, 23, is accused of repeatedly stabbing 83-year-old Peter Wrighton in the neck and head.
Mr Wrighton, from Banham, Norfolk, was found in woodland near the village of East Harling on 5 August.
Mr Palmer, of Dereham Road, Bawdeswell, was remanded by Norwich magistrates to appear before the city's crown court on Tuesday.
Mr Wrighton's body was found near the Fiveways Junction, three miles south of East Harling.
The retired BT engineer, from Banham, had been walking his dogs Gemma and Dylan when he was attacked.


Tadgh Beirne has been offered a contract extension, says Scarlets head coach Wayne Pivac.

Second row Beirne, 25, has been linked with Munster after playing a pivotal role in the Welsh region's championship victory last season.
The lock joined from Leinster and is being targeted by the team Scarlets beat in the Pro12 final in May.
"We've spoken to his agent and to Tadgh and offered him an extension on his contract," said Pivac.
"He has a bit of a dilemma in that he is playing so well that all of a sudden there are some noises coming out of Ireland.
"I don't think they wanted to know him 12 months ago, and that's why he came here to the Scarlets to get some regular rugby."
Beirne played 24 games in the 2016-17 season and scored a try as Scarlets beat Munster 46-22 in the Pro12 final at Dublin's Aviva Stadium.
Pivac believes any decision will be based on Beirne's Ireland international ambitions.
"He's one we will continue to talk to and he has another big season coming up here," said Pivac.
"If he doesn't back up his performances from last season then there won't be any noises coming out of Ireland.
"He wants to play for Ireland and who can blame him? We'll wait and see how that one pans out."
Beirne is one of more than 20 Scarlets players out of contract at the end of the 2017-18 season, including Wales internationals Scott Williams, Gareth Davies, Jake Ball and Olympics Sevens silver medallist James Davies.
Ball is on a National Dual Contract with the Welsh Rugby Union which is a similar deal to Scarlets centre Jonathan Davies.
Talks about extending Davies' contract will also continue as the Wales centre was named the British and Irish Lions player of the series against New Zealand.
"We're well down the track," said Pivac.
"Before I went to New Zealand to watch the Lions we had discussions and we've been talking to agents in the background for some time.
"We've identified the players we want to keep and we've touched base with them early.
Media playback is not supported on this device
"I'd like to think we'd get them done as soon as possible.
"We've got a good squad of guys. It's taken three years to get to this stage and we want to keep building.
"We'd like to keep the nucleus of this squad.
"There is always going to be turnover - that's professional rugby - but we've got a good core of players who we are enjoying working with.
"We don't want to break that up."


Changes to the Scotland Bill will make it  clear "beyond any reasonable doubt" that the UK government has delivered on the vow of more powers for Holyrood, the Scottish Secretary has said.

David Mundell said it would become one of the most powerful devolved assemblies in the world.
UK government amendments to the bill are due to be laid at Westminster.
The Scottish government said the changes "continue to fall short of delivering the Smith report in full".
A House of Commons debate on the bill, which brings new powers over tax and welfare to the Scottish Parliament, will take place next week.
The bill follows the Smith Commission review of devolution after last year's Scottish independence referendum.
The new powers are due to come in from April 2017. But the SNP government at Holyrood has threatened to block the bill if it believes changes to the way Scotland is funded would see them lose out.
The Scottish Secretary said: "We have listened to points raised as the bill has been debated and taken steps to improve the legislation even in areas where we believed the bill was already delivering Smith.
"For example, there has never been a power for the UK government to block welfare changes from Holyrood but we have taken steps to make it even clearer that there are no UK vetoes in this bill. We are acting in good faith and want to build consensus.
"Both of Scotland's governments have a responsibility to meet our commitments and deliver the new powers that Scotland voted for."
He added: "I am confident the House of Commons will support the Scotland Bill next week and we will enter a new phase where the Scottish government will need to start telling us how they intend to use these new powers.
"Will they top up benefits? Will they create new benefits and how much will it all cost?"
Deputy First Minister John Swinney insisted the UK government amendments had not gone far enough.
He said: "The Scottish government and the Devolution (Further Powers) Committee have set out amendments that would deliver Smith in full, including the full scope of the Sewel Convention, removal of constraints on social security powers, new powers over benefits in devolved areas and employment support, and all the Crown Estate's economic assets in Scotland, including Fort Kinnaird.
"Unless all of these amendments are accepted it is not credible to claim that the Smith Agreement has been delivered.
"It is also remains unacceptable that UK ministers can veto devolved social security powers."
The Fort Kinnaird retail park in the east of Edinburgh is part-owned by the Crown Estate but it has been proposed that it would not be included in the devolved settlement.


The family of a young referee killed in Tunisia has set up a charity to support the loved ones of terror victims.

Joel Richards, from Wednesbury, died alongside uncle Adrian Evans, grandfather Patrick Evans and 35 others in terror attacks near Sousse in 2015.
The 19-year-old Walsall fan was awarded a string of posthumous honours.
His mother Suzanne said charity Smile for Joel keeps his memory alive: "I take comfort from it - I love it, it keeps me going."
"I feel Joel's still around, I feel Ade's still here, dad's still here, because we're constantly doing Smile for Joel."
There will be 5k and 3k fundraising runs at Sandwell Valley Country Park in September.
Joel's younger brother Owen witnessed the attack and said it felt "really weird" to be called brave for his response.
He said he missed his "perfect big brother" every day.
"He was definitely someone to look up to," he said.
"He achieved so much stuff - everyone loved him."


Wolves great Roy Swinbourne has died at the age of 86.

The centre forward scored a total of 114 goals in 230 appearances for the club between 1946 and 1957.
He most famously scored twice as the then English champions beat Hungarian side Honved, which at that time provided half of the country's national team, 3-2 at Molineux in December 1954.
"Everyone at Wolves was deeply saddened to hear of the death of Roy," said chief executive Jez Moxey.
"Roy is one of the club's most iconic and revered footballers and he's left an everlasting mark on the club's history.
"He was the hero of the famous floodlit game versus Honved, which many fans say is the club's most famous victory."
Sandor Kocsis headed in fellow Hungary legend Ferenc Puskas' free-kick to help Honved lead 2-0 after 14 minutes, however a second-half Johnny Hancocks penalty and two in two minutes from Swinbourne saw Wolves win.
The Hungary national side was one of the strongest in world football in the 1950s. They won the 1952 Olympic title before inflicting a first international home defeat at Wembley on England, winning 6-3 in 1953 in a game dubbed the "Match of the Century".
The following year they thrashed England 7-1 in Hungary, a score that remains England's heaviest defeat.
Hungary went on to reach the 1954 World Cup final where they led West Germany 2-0 but lost 3-2 in Bern, Switzerland - their only defeat in 50 matches from 1950-56.
Wolves' players will wear black armbands during Monday's game at Charlton.


A 60-year-old man has been charged with a number of offences, including controlling a brothel.

The man was arrested in east Belfast on Monday.
He is also accused of controlling prostitution for gain and causing or inciting prostitution.
The man is expected to appear before Belfast Magistrates Court later on Tuesday.


Africa Cup of Nations-winning Cameroon defender Nicolas Nkoulou is taking a break from international football.

The 26-year-old scored in the Nations Cup final with a powerful header, helping his side to beat Egypt 2-1.
Nkoulou has made 74 appearances for the Indomitable Lions and is a former captain of the team.
"After winning the Africa Cup of Nations, I have a sense of having accomplished my duty for country," he told the Foot Mercato website.
"Since the beginning of my career, defending the colours of my country has always guided my steps. This mission has always constituted a motivating factor and one of my priorities.
"This decision has been difficult to take and I considered the advantages and disadvantages before arriving at a conclusion."
However, he hinted he would return to the national team, adding: "A lion never dies."


An agreement has been reached to ensure foreign workers on freight boats serving Orkney and Shetland are paid at least the minimum wage.

Transport Minister Humza Yousaf said a  new charter arrangement would end the long-running row over seafarers' pay.
The RMT union had claimed some workers on board two freight boats were paid less than Â£4 an hour.
The charter change will see contracted out services return to operator Serco Northlink from next month.
The freight vessels Hellier and Hildasay have been operated by Seatruck, which is contracted to run the service by Serco Northlink.
Seatruck argued the national minimum wage was not applicable to the crew, many of whom are non-UK residents.
Serco Northlink said it had repeatedly offered to bridge the pay gap and backdate it, but Seatruck declined to accept.
Mr Yousaf said the new arrangements would come into force early next month subject to some financial and regulatory details being finalised.
He said: "I'm very pleased to see an agreement in principle now in place to end this long running issue around the freight vessels serving the Northern Isles.
"The new charter basis will allow the wage issue to be resolved. Going forward, I can confirm that all crew members will be paid at least the minimum wage."
Serco Northlink was awarded the six-year Â£243m Northern Isles contract in 2012.
It operates three ferries and two cargo boats to the Northern Isles on a route which is heavily subsidised by the Scottish government.


Durham ensured County Championship Division One safety as they kept their nerve to beat One-Day Cup finalists Surrey by 21 runs at Chester-le-Street.

After resuming on 213-8, the hosts added another 33 before being bowled out for 246, leaving Surrey 281 to win.
Teenager Sam Curran improved his career-best from the third day, taking the final wicket to end with 7-58.
Despite Jason Roy's 96, Ben Stokes (4-54) and Graham Onions (3-62) then helped to bowl out Surrey for 259.
Mark Wood did the early damage, striking with the fifth ball of his first over and the first of his second to remove Dom Sibley and Kumar Sangakkara for ducks.
Onions, who had taken 5-90 in Surrey's first innings, then sent back Rory Burns to leave the visitors on 11-3 before Roy and Zafar Ansari began to turn things around.
Having put on 164 for the fourth wicket in the first innings, this time their stand reached 143 before Ansari (51) was trapped leg before by leg-spinner Scott Borthwick, who will be his Surrey team-mate next season.
Roy, who had earlier been close to edging Brydon Carse's first ball of the day, then became Stokes' first victim before another fighting stand of 54 for the sixth wicket between Curran (50 not out) and Ben Foakes (20).
Stokes struck twice in three balls to remove Foakes and Tom Curran, before a 30-run eighth-wicket stand between Sam Curran and skipper Gareth Batty.
But Stokes got rid of Batty before Onions polished it all off with the final two scalps, the last three wickets having gone down for just seven runs.
Last man Mark Footitt who had taken 5-90 in the first innings, had earlier taken the other morning wicket to fall, his haul of seven in the match leaving him with 31 from six Championship matches since being recalled after injury in July.
Durham rise to fifth in the table, four points behind Surrey, who they can now overtake if they can pick up four points from their meeting with relegation-threatened Hampshire at the Ageas Bowl.
Having now completed their Championship programme, Surrey's final game of the campaign is Saturday's One-Day Cup final against Warwickshire at Lord's.
Durham all-rounder Ben Stokes:
"Colly was going to take me off the over before I got Gareth Batty out, but I just felt in one of those moods when everything was clicking.
"I was running up to the crease nice and easy and it was coming out nicely, so I didn't want to give the ball up.
"I felt in decent rhythm and it was just one of those days when everything was going well for me.
"Pressure tells in a situation like that, batting last and trying to chase a total, and fortunately myself, Graham and Woody managed to bowl really well and restrict them."
Surrey skipper Gareth Batty told BBC Radio London:
"I don't feel we lost the game today particularly, I thought we batted magnificently, I felt we lost it in the first couple of days by allowing them a few too many boundary balls.
"It was a proper game of cricket played by proper players. I didn't see it as heated, it was just very good players going hammer and tongs at each other.
"That's what we play Division One cricket for. Unfortunately we were just on the wrong end of it. It could have gone either way.
"We made enough good, positive strides today to win the game, but it wasn't to be, a world-class all-rounder like Stokes had a day out and bowled beautifully, they have a good attack."


A woman has been released after being trapped under the wheel of a lorry in Aberdeen.

Emergency services were called to the scene on Wellington Road shortly after 10:00.
The Scottish Fire and Rescue Service said the woman had been freed and was being treated by paramedics.
The extent of her injuries was not yet known. The Scottish Ambulance said one woman was taken to the Aberdeen Royal Infirmary.


Glamorgan cruised to victory against Gloucestershire for the second time in five days as they won with seven balls to spare in the T20 Blast in Bristol.

Gloucestershire started slowly on a wet night, but Ian Cockbain, Kieran Noema-Barnett and Jack Taylor added 101 to help steer the hosts to post 168-8.
The visitors rallied, however, and were rewarded with a fine batting display.
Colin Ingram smashed five sixes in his 64 off 30 balls, while Aneurin Donald hit 48 not out to see them home.
Glamorgan's seamers made early inroads with the pacy Dale Steyn difficult to get away but Cockbain and Noema-Barnett both hit 37 to turn the hosts' innings around.
Gloucestershire struggled to quell Glamorgan's batting line-up and suffered when Aussie paceman Andrew Tye was removed from the attack after two high full-tosses in damp conditions.
Tye's misfortunes meant Glamorgan had few worries as they made it three wins out of four.
Glamorgan batsman Colin Ingram told BBC Wales Sport:
"You have to use the short side (of the ground), I thought we were quite intelligent in our batting tonight, and you don't have to over-hit it, just time it well.
"It's never nice to see a bowler (Tye) go through that (being taken off by the umpires), fortunately it was the over we needed to put us ahead of the rate and secure the win.
"It can happen to anyone, but bowlers are never the happiest bunch, they can be quite grumpy and he was probably frustrated, he was a bit upset.
"Credit to our bowlers for getting wickets in the early part of the innings which slowed them down, it was a great effort with a wet ball and a short boundary."


He may be just 5ft 6½in, but N'Golo Kante is a giant of the Premier League.

He is also the best midfielder in the world right now, according to Chelsea and England great Frank Lampard.
Kante was instrumental in Leicester's astonishing Premier League triumph last year and has been so effective for Chelsea this season that Eden Hazard said lining up alongside him was like "playing with twins".
Since signing Kante in July, the west London club have gone from a mid-table finish to 10 points clear at the top. Without him, Leicester are six points off the relegation zone having sacked title-winning manager Claudio Ranieri.
The 26-year-old France midfielder is energetic, adept at stopping the opposition, and arguably the most important player in the Premier League. He is also hot favourite to win numerous end-of-season awards.
But what shaped him? What makes him so good? And are Premier League academies trying to to produce the Kantes of the future?
Kante was 24 when Steve Walsh brought him to England for £5.6m in the summer of 2015.
By that stage he had spent a decade at JS Suresnes in Paris, had two seasons in the French lower leagues for Boulogne and another two years at Caen, winning promotion to Ligue 1.
By the time Kante was helping Caen consolidate their top-flight status in what would be his final season in France, Walsh had seen enough.
Now the director of football at Everton, he had a similar role at Leicester and by 2015 was in the midst of a long campaign to persuade Ranieri to sign Kante.
Ranieri wasn't so sure - he wondered if Kante lacked the size needed for the rigours of the Premier League - but every time Walsh walked past the Italian in the corridor at the club's Belvoir Drive training ground, he would whisper "Kante, Kante".
The battle for recognition, the need to persuade others of what he has to offer, is nothing new to Kante. In fact, it probably defined his formative years.
Nobody at JS Suresnes - a modest club on the western outskirts of Paris, not far from the Parc des Princes - seems exactly sure of when the tiny kid first appeared, whether it was 1999 or 2000.
He turned up on his own one day - indeed nobody at the club remembers seeing his parents in the decade he played for them.
His parents had come from Mali in 1980 and Kante grew up in a small flat in the district of Rueil-Malmaison, close to where Suresnes play. Kante's sister is in the youth system at the club.
Find out how to get into football with our special guide.
Kante was as quiet and unassuming on that day as every other throughout his time there - but there was something about him. Piotr Wojtyna coached him for years and the Pole was always impressed by both his athleticism and ability to learn.
"He was very receptive to coaching - with tactical information or positioning, where to be on the field," Wojtyna told BBC Sport.
"He always listened very carefully and the decisions he made on the pitch were very intelligent. I always put him with the weakest kids because his efforts counted for double."
Former Everton defender Sylvain Distin and Nottingham Forest winger Armand Traore also played for Suresnes, but neither were there anywhere near as long as Kante.
There is a feeling around Paris that Suresnes is a club that has its most talented players pinched by others - but not where Kante is concerned.
Suresnes is close to Paris St-Germain, but they missed him. So did Rennes, Lorient and Sochaux. The French national academy at Clairefontaine wasn't interested either.
Suresnes' deputy manager Pierre Ville thinks he knows why. "It was because he was a little guy, not spectacular. He did not play for himself, he played for the team," he said.
Photos from his time there show so clearly just how small he was, but eventually he got a move to struggling second-tier club Boulogne, 160 miles from Paris on the northern French coast. He initially joined the reserve team, the move apparently helped by Suresnes' president having a good contact at Boulogne, but at last, here was his chance.
When he arrived, he became a team-mate of current Brentford defender Maxime Colin, deputising for him at right-back. He started out in the reserve side and by the time he made his first-team breakthrough he was playing in midfield and his team had been relegated to the third tier of French football.
But, by then, Colin had seen enough to know the club had signed someone special.
"One day we did a running test. You needed to run at your maximum and it was him who killed the test," Colin told BBC Sport. "He kept running after everyone had stopped, going around the track.
"Month after month, people started to see that N'Golo was a really good player.
"I remember seeing him going to the supermarket in France with his little bag and his push scooter - he wants to do everything himself. Boulogne was very hilly but he would turn up to training on his scooter.  If you offer him a lift, most of the time he says 'no I will go by myself'. That's why he is so strong mentally, he came from really low and did all this by himself."
Perhaps wisely, Kante eventually bought himself a car but he remains unchanged. Uninterested in displaying his wealth, he now drives a Mini to training at Chelsea.
Kante says his time at Boulogne gave him the belief he could make it as a professional footballer - and when he left for Caen in 2013, he was about to take another significant step on his journey.
He played in all 38 games as they won promotion to the top flight. The following year he was a mainstay of the side that consolidated their position in Ligue 1. That season, he won the ball back more than any other player in Europe.
Walsh was about to start the process of persuading Ranieri to sign him. Kante eventually joined Leicester on the same day Crystal Palace paid a reported £7m for striker Connor Wickham.
He has been called a "machine" and a "mighty mouse", and described as your worst nightmare.
The stats speak for themselves. Since he arrived in the Premier League, he has made more tackles and interceptions than any other player. Only five players have covered more distance than Kante in the English top flight since his debut.
He doesn't seem to get injured. For a player of his position he picks up few yellow cards and has not been sent off since arriving in England.
Against Swansea in late February, a 24-second clip of Kante was widely shared - it showed him initially losing the ball but then making four tackles in quick succession. It succinctly illustrated why he is so highly rated.
Watford captain Troy Deeney speaks eloquently about what it is like to play against Kante, saying: "Whenever we broke on them last season, I always had the fear factor that Kante was coming back and I knew we didn't have much time before he got there.
"Even if I actually did have time, I always thought he might be there, so I would rush things a bit."
When you interview people about Kante - those who coached him or played alongside him - there are themes that emerge repeatedly.
His ability to cover ground, his positional sense and his humble, quiet but determined personality.
Veteran Australian goalkeeper Mark Schwarzer was at Leicester last season and watched him at close quarters. When he first saw the Frenchman, he wondered if he was a footballer because he was "so tiny" but he too was awestruck by Kante's energy.
"It was second to none," said Schwarzer. "From the very start, players would be scratching their heads and asking how he does it.
"His positional sense was incredible. He was so incredibly quiet but read the game so well. It was like you were being ambushed."
Schwarzer says Kante is a player whose talents and ability only truly emerge when you've taken the time to watch and study him, as he often did from the substitutes' bench last season.
But, when training or after a match is over, Kante just melts into the background.
Speaking in the tunnel after Chelsea's recent win at Stoke, a smile appeared on the face of Blues defender Cesar Azpilicueta when he was asked if Kante says much in the dressing room. "No," was the Spaniard's eventual answer.
Schwarzer says after Leicester's crucial victory at Manchester City last season, Kante just sat in the corner as he did after every win, quietly smiling. He was perhaps at his most animated when he played foot golf with team-mate Riyad Mahrez after training.
"He will not change his personality, he is just made like this," says Colin, who caught up with Kante after their two teams met in the FA Cup in January.
BBC pundit Phil Neville believes Kante "is the one who has knitted this Chelsea team together".
"I thought he was a number six like former Chelsea player Claude Makelele. But he is a number six, an eight and a 10 - he plays absolutely everywhere, three different positions," he said.
"I played with one of the greatest at Manchester United in Roy Keane. He got the ball off the back four, played passes, joined up with the frontman, and I think Kante is the most complete midfielder in the Premier League at the moment."
Kante's story is as refreshing as it is incredible. The small and modest man from an immigrant background who showed the persistence and determination to reach the top, but whose feet remain firmly on the ground.
But not everyone is convinced.
Burnley midfielder Joey Barton - who had a season on loan at Marseille when Kante was still at Boulogne - recently told French newspaper Le Journal du Dimanche: "At the moment, everyone swears by N'Golo Kante. It's fashionable.
"For pundits, he's the best midfielder in the world. That's not the case - he's very good, but I played against him three weeks ago.
"He's a phenomenal destroyer who played in a phenomenal team, but he's not a creator. And it's impossible to be so definitive with a player who has not played in the Champions League."
Media playback is not supported on this device
Neville agrees the question about the Champions League is valid.
"We saw he could compete in international football at Euro 2016 but I think the Champions League is a higher level," he said. "Can he do it Wednesday-Saturday-Wednesday for 50-60 games a season?
"And can he develop technically so when teams try to leave him on the ball and challenge him to pass and dictate a game, he has the answers?"
Chelsea boss Antonio Conte knows Kante can be improved.
"We are working on some aspects to try to improve him, to make him a more complete player," said the Italian.
"In the pass, yes. I think he has a lot of room to improve in the pass, and to look to make his first pass a forward pass. He can improve on these aspects, definitely."
Maybe we saw evidence of this in the recent FA Cup tie against Manchester United. Kante scored the only goal but it was his all-round performance that really caught the eye; he showed a willingness to push forward and was as much an attacking force as defensive shield.
The doubts about his ability to produce such consistently high-energy performances when he has to play twice a week will not be answered until we see Chelsea in the Champions League next season.
The day after Barcelona thrashed Paris St-Germain 6-1 in early March to pull off one of the most stunning comebacks in football history, Stoke academy director Gareth Jennings was struggling to get his point across.
Stoke had earned a superb point with a goalless draw at Manchester City on the same night Barca were running riot.
"We spoke to our boys and we were talking about Stoke and how they performed against Manchester City," Jennings told BBC Sport.
"A few of them were saying 'Yes, but did you see Barcelona?' They talk about Lionel Messi and Neymar and Luis Suarez but we want them to recognise some of the other qualities in the game as well."
Jennings is well placed to talk about the value of producing players such as Kante - he was academy director at Leicester last year before moving to Stoke in the summer.
"I went to a game last year at Bournemouth, so it was quite early in Kante's Leicester career, and I almost thought he played them on his own," said Jennings.
"He has a real discipline about him. He understands his role and what that contribution is going to be. If you are building a development programme to get the best players through your academy system, you need to make sure you are recognising those qualities, other than the ones who are technically gifted.
"I suppose the big danger is, do you miss them because you are looking for the outstanding technical player?"
Liverpool academy director Alex Inglethorpe breaks midfielders down into three categories - destroyers, energisers and magicians. Kante is certainly a destroyer and seems to fit into the middle category as well.
Inglethorpe - who managed Exeter and took a youth role at Spurs before joining Liverpool in 2012 - believes that for the academy system to work they must be able to spot and develop all three types.
Jennings agrees - arguing for this to work it is crucial clubs value all three categories.
"Talent identification is a really difficult position," added Jennings. "But there are highly skilled people out there.
"We need to make sure we are focused on all kinds of attributes. We like to talk about the world's best players and Kante and players like him need to be added to that list."
But there are questions about whether academies miss out on players like Kante because of their height - certainly, it put clubs off when he was growing up in Paris - and whether there is enough competitive football at youth level where results really matter to hone competitive, box-to-box players.
Kante came from a low base where he constantly had to impress, to overcome those who doubted him. He made the first-team breakthrough at lower-league level.
Midfielders in the academy system play in a series of leagues formed after the introduction of the Elite Player Performance Plan designed to overhaul and improve youth football.
One academy boss I spoke to wondered whether there were enough games where results mattered, where players learned how to win. In short, whether it prepared players like Kante for the real world.
Academies should ensure the preparation is appropriate, because Kante is obviously incredibly valuable.
Schwarzer says Kante was a bargain at £32m and Chelsea might struggle to keep hold of him.
Neville believes more clubs will want players like Kante - athletic, intelligent and capable of playing all over the midfield. "He will redefine what we are looking for from a midfield player," he said.
Right now, creating Kante seems more important than ever.
Additional reporting by BBC World Service's John Bennett.
Listen again to Creating N'Golo Kante, which was first aired on BBC Radio 5 live on Wednesday, 29 March


Winning Northern Ireland's assembly election would give Sinn Féin a "hugely significant worldwide propaganda boost", the DUP leader has said.

Arlene Foster said this would be a disaster for Northern Ireland, and stopping the party was the platform on which the DUP was seeking a mandate.
Mrs Foster listed 10 reasons the issue mattered if people asked about it on the doorsteps.
The former first minister was speaking at a low-key manifesto launch.
The eight-page DUP document was described as "an addendum to reflect developments since last May" - when the last assembly election was held.
It refers back to the party's five-point plan which, it said, remained as relevant now as nine months ago.
The five points were:
Mrs Foster's speech contained 31 mentions of Sinn Féin, 12 of its president Gerry Adams and just one of its new northern leader, Michelle O'Neill.
The DUP leader made no reference to the Renewable Heat Incentive (RHI) debacle which was the reason Sinn Féin gave for quitting the Northern Ireland executive last month and forcing an election.
She explained at the start of the manifesto launch that she was suffering from "man flu" and afterwards, she took no questions from the media.
In her speech, Mrs Foster said all the recent polling suggested it would be "neck-and-neck" between her party and Sinn Féin.
She attacked Ulster Unionist leader Mike Nesbitt for saying he would be giving his second preference vote to the SDLP, calling the move "sad and shameful".
"I know other parties don't like us saying it, but the reality is that every vote for another unionist party is a vote which is lost in the battle to make sure that Sinn Féin does not win this election," she said.
Mrs Foster's 10 reasons for opposing such an outcome included claims that it would:
She concluded: "It would give Gerry Adams and Sinn Féin a hugely significant worldwide propaganda boost just months after nationalism's worst election since 1993 and would undermine the unionist confidence which is being rebuilt after so many years in decline.
"And finally, it would, of course, give Sinn Féin the right to nominate a first minister - our job is to make sure that does not happen."
On the negotiations which will likely follow the election, Mrs Foster said her party did not want to construct any red lines or barriers to the restoration of the executive.
She said the DUP would honour all previous commitments, on the basis that republicans do the same.


Wales maintained their unbeaten record to to remain top of their Euro 2016 qualifying group with a precious 2-1 victory over Cyprus in Cardiff.

Chris Coleman's side appeared to be coasting as goals from David Cotterill and Hal Robson-Kanu - the latter a stylish team effort - gave them an early 2-0 lead.
But a goal from Vincent Laban and a red card for Wales midfielder Andy King set up a nervous second half.
Which players impressed and who had an evening to forget? Marks are out of 10.
Had little to do but made a hash of the Cyprus goal. A stark contrast to his man-of-the-match display against Bosnia-Hercegovina.
An energetic effort which did not wane even as Wales went down to 10 men. Distribution could have been better but defending was solid.
Marshalled the defence in a mature display, ensuring the team approached the game in a calm fashion after being reduced to 10 men.
Another fine performance from the Hull defender, who made a number of timely interventions and brave challenges.
Composed defensively and a willing support runner in attack, the Swansea City left-back contributed to an industrious team performance.
An early yellow card curbed his usual tenacity and forcing him to tread tentatively compared to his forceful display against Bosnia.
A promising first-half performance with some neat touches was spoiled by his red card, which made life very difficult for his team-mates.
Excelled in a couple of positions, whether that was out wide or as a central attacker, and took his goal smartly.
Subjected to brutal treatment from Cyprus but battled on regardless and went close with a couple of efforts.
A bright first start from the young winger, running at Cypriot defenders at every opportunity. His positivity led to the corner which produced the first goal.
Had no time to make an impact after he was taken off inside two minutes with a shoulder injury.
Scored the opening goal and kept the ball well when Wales were looking to hold on to their lead in the second half.
Brought on to solidify the midfield following King's red card and did so with a combative but composed performance.
Ran out of time to make any telling contributions on his debut.


Part of Cardiff city centre will be closed off on Saturday as 45,000 people are expected in the city for the speedway.

Motorsport fans will attend the event at the Principality Stadium, with roads closed from 15:00 BST to 21:30.
High Street, Westgate Street, Quay Street, Guildhall Place, Golate, Park Street and Scott Road will all be closed to traffic.
There will also be a queuing system in place at Cardiff Central Station.
Bus stops in the city centre will not be in use and will be relocated to either Churchill Way for those heading east, Greyfriars Road for north or Tudor Street for west.
The St Mary Street taxi rank will be closed from 15:00 to 21:30, but the Mill Lane rank is open all day.


The executive asked to come up with a plan to revive Network Rail's fortunes has said she cannot rule out recommending privatisation.

In an interview with the BBC, Nicola Shaw said that a partial or total sell-off "was absolutely on the table; it can't not be."
Ms Shaw was drafted in by the government after Network Rail's upgrade plans fell apart last summer.
Work to electrify key lines had been dogged by delays and mounting costs.
Ministers paused two of the projects, in the Midlands and across the Pennines, and replaced the chairman, while a number of reviews are carried out.
Ms Shaw, who is the boss of Britain's only high speed line, HS1, was asked to come up with a report before the Budget next spring.
She said there were a whole range of issues that had to be considered and she was keen to hear what people had to say.
She said she would also recommend changes to the regulator if necessary.
"I don't believe there is one perfect answer. I think there is something that we'll go forward with for the next period of evolution of the railway. I don't think there has to be a big row. The challenge for me is how to bring people together. To find a way forward that people will support."
The future of Network Rail - which controls 2,500 stations as well as tracks, tunnels and level crossings - has been up in the air ever since the embarrassing admission last June that, just one year into a five year upgrade plan, the company had lost control of timetables and budgets.
Problems came to a head when the company was re-classified as a public sector body in September last year.
Overnight, it meant it could no longer borrow extra money from private sources to fill the funding gap.
I've been told by those close to the situation that the impact of those changes took everyone by surprise.
It also meant the company's Â£37.7bn debt moved onto the government's books.
One source suggested that before the change "ministers might turn a blind eye" to the extra costs, as long as the job was done. This is no longer possible.
Insiders also talked of a failure to check if they had sufficient numbers of qualified engineers to carry out the necessary work.
And they underestimated how difficult it would be to upgrade and electrify the Great Western Line, which dates from Victorian times, while running a service on it.
Three reviews are under way.
Ms Shaw has a difficult job, navigating a wide range of views, including those of the unions and the new Labour leader, Jeremy Corbyn who wants to see the railways  back in public hands.
"I am talking to unions, and to representatives of staff and to other members of different parties so I hope we have strong engagement because I think it matters."


Three people have been arrested on suspicion of murder after a man died in hospital following an assault outside a nightclub early on Boxing Day.

Zac Wells, 30, of Wallasey, Merseyside, suffered head injuries in the incident, which happened at about 03:45 GMT near Evo's Loft nightclub in New Brighton.
A 29-year-old man from Poulton, a 16-year-old boy from Egremont and a woman, 26, from Birkenhead, remain in custody.
Merseyside Police have appealed for witnesses to come forward.
The force said Mr Wells' family were being given specialist support following his death earlier on Wednesday.
Det Insp Gary Stratton said: "We are determined to find out exactly what happened.
"We are particularly keen to speak to anyone who was in Evo's Loft nightclub before the incident took place, or anyone who was outside and witnessed the incident or its immediate aftermath."


One of America's largest circus companies has said it will phase out the use of elephants in its shows.

The Ringling Brothers and Barnum & Bailey Circus told that it plans to stop using the animals by 2018.
It said growing public concern about how the animals are treated led to the decision.
The company's 43 elephants will live at an animal conservation centre in Florida.
The circus will continue to use other animals - such as lions, tigers, horses, camels, and dogs - in its performances.
In recent years, some cities and counties have passed laws banning the use of elephants for entertainment, which has complicated the show's tours, company president Kenneth Feld.
Animal right activists have protested the use of the elephants in live shows for years saying they face physical abuse at the hands of trainers and unhealthy living conditions.
"Many of the elephants are painfully arthritic, and many have tuberculosis, so their retirement day needs to come now," said Jessica Johnson, a spokeswoman for People for the Ethical Treatment of Animals. "If the decision is serious, then the circus needs to do it now."
Executives from Feld Entertainment, which owns the circus company said the decision was not easy and was the result of much debate.
"There's been somewhat of a mood shift among our consumers," the company's executive vice president Alana Feld told the Associated Press.
"All of the resources used to fight these things can be put towards the elephants," Mr Feld said. "We're not reacting to our critics; we're creating the greatest resource for the preservation of the Asian elephant."
Feld Entertainment owns 43 elephants, of which 29 currently live at the company's 200-acre conservation centre in central Florida. Until 2018, 13 of the animals will continue to perform in shows. One elephant has been loaned to the Fort Worth Zoo for breeding.
The company plans to formally announce the decision on Thursday.
Elephant acts have long been a part of the company's show, and have often been featured in its advertising materials.


Swiss prosecutors are investigating claims Turkish citizens living in Switzerland are being spied on.

Swiss federal prosecutors said they had "concrete indications" pointing towards political espionage, but refused to say who they were targeting.
It came a day after the Swiss foreign minister told his Turkish counterpart Swiss authorities would investigate any illegal intelligence activities.
Turkey is due to hold a controversial referendum next month.
The referendum would give President Recep Tayyip Erdogan sweeping new powers. But in order to get it through, he needs to win the vote of Turks living at home and the more than four million citizens living abroad.
Read more:
But his attempts to hold "Yes" rallies in a number of European countries have been blocked, leading to rows with both Germany and the Netherlands, as well as the wider European Union.
Switzerland, home to more than 70,000 Turkish nationals, has tried to stay neutral. However, local media reported Turks critical of Mr Erdogan's government were being spied on during a lecture at the University of Zurich earlier this month.
More recently, a member of Switzerland's upper house of parliament filed a lawsuit accusing two Turkish organisations of spying on Turkish citizens and dual nationals living in Switzerland, and requested an  investigation.
On Friday, the office of the attorney general said in a statement it "has been made aware of concrete suspicion that political espionage has likely been conducted involving the Turkish community in Switzerland", confirming it had opened the investigation on 16 March.


Atheist author Prof Richard Dawkins has congratulated the people of Wales after nearly a third of them revealed in the 2011 census that they have no religion.

The evolutionary scientist, whose books include The God Delusion, said Wales was "ahead of the rest of the UK" in showing a decline in religious belief.
The census found 32% in Wales have no religion, against a UK figure of 25%.
The Church in Wales said Christianity was "no longer the default setting" for many, but the picture was complex.
Of those in Wales who described themselves as believers, the number of Christians fell by 14 percentage points to 57%.
Prof Dawkins said: "I congratulate the people of Wales in coming out ahead of the rest of the United Kingdom in this respect - well done."
He told BBC Radio Wales' Good Morning Wales that he believed in the "wonder" of scientific truth.
He said: "People who are educated in religion are positively encouraged not to investigate, not to think sceptically about why they are here, but instead to accept what people wrote 2,000 years ago.
"I guess we do need focal points for communities but you can say also that religion has been a focal point for all sorts of backward, indeed bigoted, thinking about homosexuality, about abortion, the right to die, that we're seeing at the moment."
He added that research commissioned by his foundation meant that the outlook for Christianity in the UK was "even more pessimistic" than the census data suggested.
He said many of those who put themselves down at Christian did so because they thought of themselves "as a good person" rather than due to belief in the virgin birth, or of Jesus Christ as the son of God.
Prof Dawkins dismissed the figures for people saying they were a Jedi knight or that heavy metal music was their religion as "a kind of protest" against the inclusion of a census question on religion.
The census found those in Wales who are Muslim was 1.5%, up from 0.7% in 2001, while there were also slight increases Hindus or Buddhists, both up from 0.2% to 0.3%.
There was also a rise in people saying they had other faiths, from 0.2% to 0.4% while the percentage who said they were Sikh or Jewish remained unchanged between 2001 and 2011 at 0.1%.
Churches said they were not discouraged by the findings, and argued that Christian belief was still clearly alive and well.
Following the census results, the Church in Wales said: "It should also be borne in mind that statistics can't show the whole picture in matters of faith.
"The past few months, for example, have seen people in different parts of Wales turn to churches in their thousands following various tragic events: in Machynlleth, in Ely, in St Asaph.
"People find God when life gets tough and it is the church's privilege to be there for them whenever and wherever we may be needed."


Nigeria is one of the world's fastest growing markets for champagne and private jets, thanks to a booming economy boosted by the thriving sectors of mobile phones, banking and Nollywood.

There are at least 138 private jets registered in the country, according to Bombardier.
The country became Africa's largest economy in 2014, if the latest overhaul of statistics is to be believed. Changing the base year calculations from 1991 to 2010 certainly seems to have had a flattering effect.
Nigeria has also become the region's top destination for foreign direct investment, with inflows now no longer just concentrated on the oil and gas industry.
Multinationals, such as NestlÃ©, Heineken, SABMiller and Unilever, are pouring in millions of dollars to expand production, shrewdly tapping into the rich consumer market of the emerging middle classes of Lagos and Benin.
Newcomers Procter & Gamble and Nissan are also wading in, investing in manufacturing and assembly plants, while General Electric is investing in power.
However, its spectacular growth has been somewhat checked in the last 12 months by the threat of the Islamist militant group Boko Haram.
Large-scale attacks, including the abduction of over 200 schoolgirls last year, has taken its toll on local businesses in the poverty-stricken northern states, where the terrorist group has gained most ground.
Currently, the three northern states of Adamawa, Borno and Yobe are under a state of emergency due to the increasing violence.
The local chamber of commerce estimates that business activity in Kano has dropped by 80% over the past three years.
Sa'id Dattijo Adhama, the owner of a textile business in the city of Kano, says: "Lots of projects are being cancelled in the region because people are scared.
"They are scared that factories can become targets; commuters to work can also become targets; and this is impacting everyone here.
"Lots of women here normally work part-time or sometimes full-time. They cannot anymore. It is too dangerous for them - even the employers do not want to hire them.
"So, families are suffering - they might have had two incomes before, now they only have one."
The only economic impact the group has had so far is in slowing down production in the regions that are already struggling.
Many analysts feel that the spoils of growth and prosperity are concentrated on the few, as nearly 70% of the population lives below the poverty line, according to the National Bureau of Statistics.
Many in the south of the country feel that the threat of Boko Haram, whilst unfortunate, is confined to the north.
The economic divide between the two regions, if superficial before, is now very much entrenched.
David Ladipo, managing director of energy company Azura Power West Africa, says: "We're diversifying now. Non-oil sector growth is 7% - Nigeria's infrastructure is changing and foreign investors are not deterred.
"My business focuses on the electricity sector and I don't have problems with foreign investors despite it being an ambitious venture."
The rise of extremist Islamic militancy has come at a time when the price of oil has dropped to $55 a barrel, posing a larger threat to Nigeria's economy.
"The north-eastern states make up a small fraction of Nigeria's economy," says Jon Ashbourne, Africa economist at Capital Economics.
"Estimates say those affected states account for 7% of the economy, and Boko Haram is only active in a portion of those states.
"Whereas oil accounts for 90% of Nigeria's exports and over three-quarters of government revenue. So the falling price of oil has meant that government spending has had to be cut back."
The oil price fall may have also led to the devaluation of the Nigerian currency, the naira, which fell 7.5% against the dollar last year.
"The currency weakening is also worrying," says Mr Ashbourne. "Nigeria imports lots of goods, including fuel and food, so the cost of the essentials will increase."
Capital Economics says it has cut its 2015 growth estimate for Nigeria from 6.2% to 4% as a result.
Boko Haram is threatening to bring its insurgency to Lagos and the oil fields of the Niger Delta - the southern regions that drive the economy. Growth could suffer significantly if militants succeed in bringing mayhem to Lagos, economists fear.
As poverty persists across the country, the number of Nigerian millionaires will jump by 47% over the next two years, say analysts at New World Wealth.
Last year, whilst attacks accelerated in the central city of Abuja, the World Economic Forum still held its meeting there, just weeks after the schoolgirls went missing.
And in Lagos, start-up incubators, fancy cafes and luxury car dealerships continue to multiply across the city.
"We feel for our fellow countrymen, of course," says Mr Ladipo. "And it saddens me every time I hear about another attack.
"But this country is still an attractive market for businesses both large and small around the world. The evidence is clear."


A father-of-two from Liverpool, Joseph Clark was a fork lift driver and drove to the match with his brother Stephen Clark and David Roberts, who both survived, and another friend, Alan McGlone, who also died in the tragedy.

This is the full statement to the inquests read by his son, Stephen Clark, on behalf of his mother Jacqueline Gilchrist:
Jacqueline Gilchrist speaking on behalf of the Clark family.
Joseph Clark came from a large family. He had five brothers and one sister. He was the third eldest and always loved spending time with his extended family when he was growing up.
'Oey' was quite a shy lad who enjoyed playing football and going out with his mates and brothers. He was very close to his siblings, as well as his Mum and Dad.
Profiles of all those who died
He loved it when his extended family had large gatherings. He got to meet those relatives he hadn't seen for a while. Even his aunts and uncles loved him.
Joseph, who was also known as Oey, played football for two local teams and was known for being a speedy winger. One of the teams he played for was the Woodpecker Bar FC.  People always commented on how good a player he was, even if he was just kicking a ball about with his mates.
Oey and I met in 1978. I was 16 years old and Oey was 18. We lived around the corner from each other.
'Fell in love'
We met in a club and from then fell in love. We loved each other to bits, and then, four and a half years after we met, we had our first son Joseph, who was born on 31 August, 1982.
Sadly, we lost Joseph on 15 October when he was just six-and-a-half weeks old. Oey was heartbroken.
Stephen was born two years later, on 22 March, 1984. Oey was over the moon and was so excited that he had a son. He nicknamed him BB. They were always playing football together and going on days out on boats up the Mersey.
In 1989, we gave birth to a little girl Jennifer. She was tiny. Oey was scared to pick her up.
The morning of 15 April, 1989, that horrible day, was one of the times that he did pick her up before he left the house. He had been playing football with Stephen outside while holding Jennifer in his arms and swinging her in the air.
His mates arrived in the car to go to the match, so he gave us all a kiss and said 'See you later' and off he went. That was the last thing that he said to us because he never came back from the match.
He was only 29 years old with his whole life in front of him.
'Happy-go-lucky'
Oey was employed by IBL in Liverpool and enjoyed his time working there.
We all miss Oey very, very much. Life has never been the same since he died that horrible day. Our whole lives changed and I never really got over it and we're in still life. I am still the same from that day.
Oey would have been proud of his children now that they are grown up. Stephen remembers lots about him, going to matches with his father and enjoying the time  that they spent together.
He loved Liverpool Football Club and I know that he was very proud to be able to take his own son to the matches at Anfield.
Oey has three beautiful grandchildren, who he never had the chance to meet. The eldest, Joseph, was born on New Year's Eve ,2005. Lee was born in 2008 and his  grand-daughter, Daisy, was born on 27 July, 2012 but unfortunately Daisy only lived 12 days before she passed away.
Joseph loved life to the full. He was always happy-go-lucky and forever with a smile on his face. He is missed by all of us who were lucky enough to have known him.


Batsman Ian Bell will not see being dropped from England's Test squad for the tour of South Africa as the end of his international career, says pace bowler Stuart Broad.

Five-time Ashes winner Bell, 33, who has played 118 Tests, has been dropped from the four-match series, which starts in December.
Bell has not scored a century in 23 Test innings.
Former England batsman Kevin Pietersen labelled the decision "pathetic".
Media playback is not supported on this device
England wicketkeeper Jos Buttler called it a "tough situation" for Bell, while former head coach Peter Moores told BBC Radio 5 live that the player has "got some cricket left in him".
Bell has already said he is "absolutely gutted" to miss out, but "determined" to win his place back.
Nottinghamshire pace bowler Broad, who is in the squad, added that Bell was a "world class" player who would bounce back.
"He will be very determined to work hard and get back in," said the 29-year-old.
"We know in cricket that opportunities do arise and, although he is not in this Test tour to South Africa, he won't see that as the end of his career.
"He will be working hard after a bit of a break to improve, put runs on the board and get back in this England side.
"You can be one injury away from getting your spot back and he will work on his game. I am sure he won't rest. He will be very focused."
Pietersen, who last played for England in January 2014, said Bell's omission was "ridiculous".
"You have to take him for his experience," added the 35-year-old on a video hosted by breathesport.com.
"It is pathetic. I think he has been hard done by here."
Moores, sacked by England in May, said Bell will understand the decision to drop him.
"Ian's going to be very disappointed but he also knows the nature of sport means if you're not performing to the top level you're exposed to being left out," he said.
"It'll have been a very tight decision but he also understands he's not put the runs on the board and that's given the selectors the opportunity to look at someone else."
Buttler, 25, who lost his place as Test keeper to Jonny Bairstow in the final match of the recent Pakistan series but remains in the one-day side, told BBC Sport: "He is obviously determined to win his place back which shows great professionalism."


Plans to reintroduce the Eurasian lynx 1,300 years after it became extinct in the UK will be submitted soon, campaigners have said.

The Lynx UK Trust wants to import up to six of the cats from Sweden to Kielder Forest in Northumberland.
With a public consultation over, the trust said the five year trial plan would go to Natural England by September.
It has been criticised by some residents and sheep farmers.
The scheme would see four to six lynx wearing radio tracking devices with Kielder chosen due to its dense woodland and low number of roads.
The trust said the animals would help control deer numbers as well provide a tourism boost.
Dr Paul O'Donoghue from the trust told the Guardian the lynx "belongs here" and is an "intrinsic part of the the UK environment".
He also told the paper he hoped the lynx could be in the forest by the end of the year.
Sheep farmers fear the animals could target their livestock although the trust said the cats would hunt in woods rather than fields.
The trust did admit, however, that some sheep could be killed but farmers would be "generously compensated" for any losses.
Phil Stocker, chief executive of the National Sheep Association, said there were several hundred sheep farmers around Kielder, any one of whom could be affected by the lynx.
He said valuing a sheep was complex and, money aside, there were major welfare concerns.
Mr Stocker said people would not accept animals facing "unnecessary pain" and one sheep being attacked by a lynx could cause major stress and possible damage to others in the flock.
He said the UK no longer had the "landscape" for the lynx to be "genetically sustainable" and it would not be in the cat's interest to be reintroduced into an environment that, thanks to roads and industry, has changed so much since the cat existed here.


Police are dealing with a significant rise in calls about drones amid the growing boom in "cameras in the sky", figures released to BBC Wales show.

South Wales Police saw the biggest increase, with 38 separate incidents over the past year - up from only four during the previous three years.
Gwent Police had 19 complaints in 2015-16 and Dyfed-Powys had nine. North Wales Police had just one since 2010.
Drones were also reported over Swansea Prison twice last year.
A Freedom of Information (FOI) request revealed both the drone and a mobile phone were seized in the first incident, although no suspects were traced on either occasion.
Anyone found using drones in an attempt to get contraband into prisons could be punished with a jail sentence of up to two years.
Meanwhile, a second FOI request revealed the increase in calls to police in Wales about drones had increased in 2015-16.
They showed:
Drones are becoming increasingly accessible, with advances in technology leading to many people being able to afford a small device, often with a camera attached. Some basic models now cost less than Â£100, with more advanced types commonly available for Â£700-Â£1,000.
The CAA and police around the UK have successfully carried out four prosecutions for drone misuse, all resulting in fines.
The use of drones is governed by the law, and the CAA has a set of rules called the "drone code".
For instance, they must not be flown higher than 400ft (about 122 metres), users must be able to see them at all times, and drones with cameras cannot be flown within 50 metres (164ft) of people, vehicles, buildings or structures.


A request to take pioneer Amy Johnson's aeroplane to her home city of Hull has been refused by the Science Museum.

Ms Johnson became the first woman to fly solo from the UK to Australia when she managed the feat in 1930.
Organisers of a festival to mark the 75th anniversary of her death hoped to put her Gipsy Moth on display in Hull.
But the Science Museum in London turned down the proposal, explaining it would cost "several hundred thousand pounds" to move the historic aircraft.
Rick Welton, director of the Amy Johnson Festival, said he was "disappointed" by the decision.
"I'd like to have more detailed discussions about the loan of the aircraft," he said.
"I think it needs a bit more open-mindedness from the Science Museum.
"People in the city would be so excited to have the plane back - I'm sure we could get some kind of crowd funding."
A Science Museum spokesman said: "The Gipsy Moth is one of the highlights of our permanent flight gallery and is seen by more than one million visitors each year.
"We did receive a loan request last August but decided not to lend it as removing the Gipsy Moth would have cost several hundred thousand pounds and caused considerable disruption for visitors to the museum."
Ms Johnson was born in St George's Road, Hull, on 1 July 1903.
Her solo flight to Australia took 19 days and she landed in front of a huge crowd in Darwin on 24 May 1930.
The 37-year-old died in mysterious circumstances during World War Two when the RAF plane she was transporting crashed in the Thames Estuary on 5 January 1941.
Her body has never been found.


Authorities in Indian-administered Kashmir have lifted a curfew in many parts of the Muslim-majority valley after more than 50 days.

Curfew was imposed after an upsurge of violence since 9 July.
The protests were sparked by the killing of a popular militant leader Burhan Wani.
More than 60 people, mostly young men, have been since killed in clashes between protesters and security forces and thousands more have been injured.
This is the worst violence seen in the region for years.
Kashmir's 'curfew schools'
Police said the 51-day-old curfew has been lifted from most parts of the valley, except in Pulwama district and some parts of Srinagar, on Monday.
Prime Minister Narendra Modi said on Sunday that "those inciting violence" in Kashmir "will be held accountable one day".
He said "if any life is lost in Kashmir it is our loss, a loss of our people and our country".
The killing of Wani, 22, sparked days of deadly violence in the valley.
India considered Wani a terrorist, but for many locals he represented the spirit and political aspirations of a new Kashmiri generation, correspondents say.
Indian officials have said he was instrumental in persuading local boys to take up arms.
The state government has said it will investigate reports of excessive police violence towards unarmed protesters.
The last bout of serious violence in the region was in the summer of 2010, when more than 100 people died in anti-India protests, which broke out after police shot dead a teenager.
Disputed Kashmir is claimed in its entirety by both India and Pakistan and has been a flashpoint for more than 60 years, sparking two wars between the countries.
Within the disputed Muslim-majority territory, some militant groups have taken up arms to fight for independence from Indian rule or a merger with Pakistan.


The funeral of the Irish coastguard pilot killed in a crash off the coast of County Mayo has taken place.

Captain Dara Fitzpatrick died after the Irish Coastguard Rescue 116 helicopter crashed on Tuesday.
Hundreds of mourners gathered for her funeral at St Patrick's Church in Glencullen, Co Dublin.
Captain Fitpatrick's parents, four siblings, her son Fionn, and other family members accompanied the coffin into the church.
The Coastguard helicopter did a fly past at the funeral.
Parish Priest Fr Andrew O'Sullivan said St Patrick's church had seen many sad and tragic funerals but few as sad and sorrowful as this one.
He paid tribute to the Fitzpatrick family and said they and the community had lost a "loved and valued member".
He said their thoughts were with Captain Fitzpatrick's three crew members who are still missing.
Dara Fitzpatrick's sister told the funeral mass that "God owes us, he owes us to bring home Dara's three colleagues who are still missing".
Mourners included members of the Coast Guard who formed an honour guard before the 11:00 funeral Mass.
The President of Ireland, Michael D Higgins was in attendance, along with Taoiseach (Irish Prime Minister) Enda Kenny.
Also present were members of the RNLI, Civil Defence, mountain rescue and many other groups.
A signal from the helicopter's black box had been located close by but poor weather conditions have hampered efforts to find the device.
The main focus of the search operation is to locate three missing crew.
Agencies involved in the operation say it may be some time before they can try to access the area where they believe the wreckage of the aircraft is located.


Spending per pupil in schools in England is likely to fall by 8% in real terms over the next five years, the Institute for Fiscal Studies warns.

It argues that school funding levels will feel quite different in the next five years from the previous five.
Schools are set to face real-terms reductions in spending per pupil for first time since the 1990s, it adds.
The report, however, says schools have been protected in recent years compared with other government departments.
Although there will be similar growth in nominal spending to that in the last Parliament, resources will shrink because of rising costs and increasing pupil numbers, it says.
Key cost increases include:
"Taking these together with pressures on other costs, we forecast that school spending per pupil is likely to fall by around 8% in real terms [based on a school-specific measure of inflation] between 2014-15 and 2019-20," the report says.
But a spokesman for the Department for Education said: ""We are protecting the schools budget, which will rise as pupil numbers increase and have made significant progress towards fairer funding for schools.
"This government is committed to making sure schools are funded fairly so all pupils have access to a good education - a key part of our core mission to raise standards across the country and make sure every child reaches their full potential."
The National Union of Teacher said many schools and colleges were already struggling.
Deputy general secretary Kevin Courtney  said: "At a time when we face major problems with teacher supply, IFS notes that the government's pay cap of 1% could make recruitment and retention more difficult.
"With pupil numbers rocketing, we need to recruit more teachers just to stand still and we need to invest in capital funding to provide the new places needed."


Edinburgh Airport has unveiled details of a five-month trial of a new flight path for departing aircraft in a bid to increase capacity.

The Airspace Trial, which will begin on 25 June, will introduce a new Standard Instrument Departure (SID) route.
Airport bosses said the new route would allow aircraft to take off at one-minute intervals.
They said it would allow the airport to maintain safe and sustainable growth without affecting punctuality.
Edinburgh is Scotland's busiest airport, with more than 40 airlines serving more than 100 destinations.
Last year, more than 10 million passengers passed through, making it the busiest year ever for a Scottish airport.
Most of the time the flights take off west towards Newbridge into the prevailing wind.
The airport currently uses three SIDÂ€Â™ routes -  known as Grice (which goes north), Gosam (which goes south west) and Talla (south).
The new route - Tutur - will see aircraft take off in a south westerly direction and turn right towards the River Forth, passing over West Lothian and to the east of Linlithgow.
Aircraft will climb as they fly above the river before flying back over land at approximately 13,000ft near Musselburgh racecourse in East Lothian.
David Wilson, chief operating officer of Edinburgh Airport, said: "At the moment, Scotland's aircraft currently fly on a network that was designed in the 1970s.
"What we're aiming to do is begin upgrading the airspace above Edinburgh Airport and bring it into the 21st Century."
He said the trial would give more modern aircraft the opportunity to take off on a new westerly departure route.
Mr Wilson said: "We've taken great care to design this new departure route with the utmost consideration for our neighbours.
"The route passes over very few populated areas and flies over the river for the bulk of its flight path."
He said the trial would monitor the impact on local communities and noise monitors would be placed along the flight path to collect data on the flights.
Councillor Gavin Corbett, of the Scottish Greens, said he would like to see a more fundamental review of travel capacity.
He said: "For example, almost half of Edinburgh Airport's traffic is domestic traffic. That's the kind of traffic which should be on the railways and perhaps that's the way forward."
Glasgow Airport is also reviewing its airspace.
Along with Edinburgh and Prestwick airport, it is part of the Scottish Airspace Development Design Group, formed last year to review capacity and future growth of air travel in central Scotland.
A spokesman for Glasgow Airport said: "Scotland's aircraft currently fly on a network designed in the 1970s and there will be a requirement for this to be upgraded.
"We are currently working to understand what this means for Glasgow Airport, however, we will consult fully with relevant stakeholder groups, community representatives and other interested parties prior to any trials."


Oxford United have signed Everton striker Conor McAleny on loan until the end of the season.

McAleny, 24, has played twice for Everton and has most recently been on loan at Wigan Athletic last season, when he netted four times in 13 games.
Oxford boss Michael Appleton told the club website: "He works hard, knows where the goal is and we think will give us another goal threat."
Oxford are 14th in League One and into round five of the FA Cup.
Find all the latest football transfers on our dedicated page or visit our Premier League tracker here.


British swimmer and world-record breaker Adam Peaty answer some of your questions!

3 August 2017 Last updated at 16:57 BST
He's just got back from the Swimming World Championships in Budapest, Hungary, where he won two gold medals.
He also broke his own world record, twice!
Find out how he keeps himself motivated, what sport he'd choose to do other than swimming and what it takes to get a six pack.


Network Rail has indicated that it will not be changing the name of the Exhibition Centre station in Glasgow following a rebrand of the Scottish Exhibition and Conference Centre.

On Thursday the SECC changed its name to the Scottish Event Campus (SEC) to incorporate the Clyde Auditorium (Armadillo) and The SSE Hydro.
A Network Rail spokesman said it rarely changed station names.
He said such a change could involve spending a six-figure sum.
"Those funds can usually be better spent elsewhere on new infrastructure," he said.
He said high costs were incurred in a name change due to a number of factors, including updating nationwide computerised booking, timetabling and signalling systems as well as more localised costs such as new signage, new network maps and rerecording in-station/on-train announcements.
Live entertainment has now become a significant part of the SEC's business.
SEC chief executive Peter Duthie said the rebrand aimed to reflect the changes to the business over the past 30 years and to showcase the company's ability to stage large-scale events.
He added that, historically, the company had found that many people did not realise all of the buildings were part of the SECC.
When it was originally built in 1894, the station was called Stobcross. It closed in 1959 and after a 20-year absence reopened in 1979 as Finnieston. It was renamed the Exhibition Centre in 1986.


Lawyers for two Australian drug smugglers on death row in Indonesia say they will continue to fight for them, after losing a legal challenge.

Andrew Chan and Myuran Sukumaran, the leaders of the "Bali Nine" group of heroin smugglers, are set to be executed in Indonesia soon.
On Monday a court ruled they cannot challenge the president's decision to refuse them clemency.
But their lawyer said the case would now go to the constitutional court.
"We believe that these men over the last 10 years have rehabilitated themselves and we are very concerned that that fact has not been properly and genuinely considered by the Indonesian authorities and the Indonesian legal system," Michael O'Connell told the BBC.
"There is no further appeal that lies in the administrative court, however... Andrew and Myuran will file an application in the Indonesian Constitutional Court challenging the interpretation of the clemency law and arguing that the president has an obligation to properly and genuinely consider their exceptional rehabilitation."
The application would be filed this week, he said, with a preliminary hearing expected "a week or two afterwards".
Both men had clemency appeals rejected by Indonesian President Joko Widodo earlier this year.
Mr Widodo, who took office last year, has a policy of denying clemency to drug offenders, saying the drug trade has caused huge damage to Indonesia.
In January he authorised the executions of six drug offenders, including five foreigners. The two Australians are in a second group, of 10 foreign nationals, to be put to death.
No date has been set for the executions, however. Indonesian authorities say they are waiting for all legal avenues be exhausted in all of the convicts' cases before the group are executed.
On Monday, responding to news of the constitutional court challenge, Indonesian Attorney-General Muhammad Prasetyo said: "The legal process is already done."
"This proves that they are simply trying to buy time. We can say they are playing with justice," the AFP news agency quoted him as saying.
But another lawyer for the men, Peter Morrissey, told the Australian Broadcasting Corporation that the aim was to get the men's cases for clemency properly heard, not "some delaying tactic".
"No matter what our opponents might like to say or how they'd like to get around it, this is litigation."
Australian Foreign Minister Julie Bishop, in a statement on Monday, said it was "important that all legal processes are allowed to run their course".
Chan and Sukumaran were arrested in Bali in 2005 while attempting to smuggle heroin to Australia. A court ruled that they had organised a nine-member smuggling operation.
But their families have argued that they are now reformed characters and should be shown mercy. Australia has also mounted a passionate diplomatic campaign on their behalf.
Indonesia has faced criticism from other countries whose nationals are facing execution. The group of 10 includes people from Brazil, France, Nigeria and the Philippines among others.
Who are the Bali Nine?


Brendan Taylor is bracing himself for a rowdy welcome when Nottinghamshire travel to Chelmsford to face Essex in the One-Day Cup semi-final on Friday.

Taylor scored 154 off 97 balls in a thrilling 24-run win over Somerset to help Notts progress to the last four.
The former Zimbabwe captain told BBC Radio Nottingham: "We want to field first before the beers kick in.
"But whatever we do we will have to do it very, very well. If we are not on it 110% we can be found out for sure."
Notts last won the trophy in its previous format as a 40-over competition in 2013, beating Glamorgan by 87 runs in the final at Lord's.


Two US inmates who were on the run since Tuesday after shooting dead two prison officers have been captured, officials say.

Donnie Rowe and Ricky Dubose were seized in the state of Tennessee.
The men overpowered the guards as they were transported by bus to another facility in the state of Georgia.
This triggered a massive nationwide manhunt, with the authorities warning that the public was in "grave danger" because the inmates were armed.
On Thursday, officials said the two men were in custody following a car chase in rush hour traffic through Rutherford County, Tennessee.
Earlier that day, the two men had stormed into an elderly couple's home, put guns to their heads and tied them up with a belt, authorities say.
Dubose and Rowe remained inside the home of the couple - who police say are "extremely traumatised" - for three hours as they took clothing and jewellery, and ate beef stew.
After the convicts left in the couple's black Jeep Cherokee car, the man and woman managed to escape and call police.
Rutherford County Sheriff's Office deputies spotted the black Jeep at around 18:00 local time about 50 miles (80km) southeast of Nashville and followed, leading to a car chase reaching speeds of over 100mph.
The suspects shot at police during the chase, but deputies did not return gunfire, Rutherford County Sheriff Michael Fitzhugh told reporters on Thursday night.
After Dubose and Rowe crashed their car, they ran towards another house and tried to steal the car in the driveway.
But an armed homeowner held the two at gunpoint with the help of a neighbour before police could arrive.
On Tuesday, police said Rowe and Dubose, who were both serving time at Baldwin State Prison for armed robbery, had taken control of a prison transport bus on Highway 16 - between the towns of Sparta and Eatonton.
"They were inside the caged area of the bus," Sheriff Sills said at a press conference. "How they got through the locks and things up to that area I do not know."
The prisoners "overpowered" the guards and "they then disarmed them and one of the subjects shot and killed both guards", according to a bulletin issued by the Putnam County Sheriff's office.
Sheriff Sills on Thursday night said he was "elated" by the capture of the "vicious hoodlums".
The authorities described the fugitives as "dangerous beyond description".
Correctional officers Christopher Monica, 42 and Curtis Billue, 58, were both killed, the Georgia Department of Corrections confirmed.
Georgia Governor Nathan Deal ordered flags at the state capitol to fly at half-mast on the day of their interments.
"Rest assured, justice will be served," Mr Deal said in a statement thanking law enforcement.
"The pain endured by the families and loved ones of Sergeant Christopher Monica and Sergeant Curtis Billue endures, however.
"We will do everything in our power to support their loved ones, and we will not forget their sacrifice and service."