Two of the three British nationals killed when a Ukrainian plane crashed in Iran have been named.
BP engineer Sam Zokaei and Laing O’Rourke engineer Saeed Tahmasebi were on board the plane that set off from Tehran towards Kyiv.
They were among the 176 people from seven countries who died.
Ukraine International Airlines flight PS752 crashed just after taking off from Imam Khomeini airport at 06:12 local time (02:42 GMT).
The airline said the plane underwent scheduled maintenance on Monday.
As well as the three Britons, the victims in the crash included 82 Iranians, 63 Canadians, 11 Ukrainians – including all of the crew, 10 Swedes, four Afghans and three Germans, Ukraine foreign affairs minister Vadym Prystaiko said.
Rescue teams have been sent to the crash site but the head of Iran’s Red Crescent told state media that it was “impossible” for anyone to have survived the crash.
Tributes have been paid to the two British men who have been named as having been on board the flight.
In a statement, BP said “with the deepest regret” that its colleague, Mr Zokaei, from Surrey, was among the passengers. He had been on holiday.
“We are shocked and deeply saddened by this tragic loss of our friend and colleague and all of our thoughts are with his family and friends.”
Meanwhile, Laing O’Rourke – who Mr Tahmasebi worked for in Dartford – said: “Everyone here is shocked and saddened by this very tragic news.
“Saeed was a popular and well respected engineer and will be missed by many of his colleagues. Our thoughts are with his family and friends at this most difficult time and we will do all we can to support them through it.”
‘Humble and generous’
Mr Tahmasebi – whose full name was Saeed Tahmasebi Khademasadi – was also a part-time PhD student at Imperial College London’s Centre for Systems Engineering and Innovation.
A spokeswoman for the university said: “We are deeply saddened at this tragic news. Saeed Tahmasebi Khademasadi was a brilliant engineer with a bright future.
“His contributions to systems engineering earned respect from everyone who dealt with him and will benefit society for years to come.
“He was a warm, humble and generous colleague and close friend to many in our community. Our thoughts and sincere condolences are with Saeed’s family, friends and colleagues, as well as all those affected by this tragedy.”
At Prime Minister’s Questions earlier, Boris Johnson and Labour leader Jeremy Corbyn both said their thoughts were with the families of those killed.
A UK Foreign Office spokesman has said: “We are deeply saddened by the loss of life in the plane crash in Iran overnight.”
They said it was “urgently seeking confirmation” about how many British nationals were on board and would be supporting any families affected.
Melinda Simmons, British ambassador to Ukraine, said her thoughts are with those affected.
Ukraine’s state aviation service has forbidden its national airlines from using Iranian airspace from Thursday, with the restrictions in place until an investigation into the cause of the crash has concluded.
Ukraine’s embassy in Tehran and Iranian state television both initially said technical issues caused the crash.
But the embassy later removed this statement and said any comment regarding the cause of the accident prior to a commission’s inquiry was not official.
Ukraine said its entire civilian aviation fleet would be checked for airworthiness and criminal proceedings would be opened into the disaster.
The country’s president warned against “speculation or unchecked theories regarding the catastrophe” until official reports were ready.
Ukrainian International Airlines said the flight disappeared from radar just a “few minutes” after take-off.
The Ukrainian national carrier said according to preliminary data there were 167 passengers and nine crew members on board but its staff were “clarifying the exact number”.
“The airline expresses its deepest condolences to the families of the victims of the air crash and will do everything possible to support the relatives of the victims,” a statement said.
The airline, which is investigating the crash, said the aircraft – a Boeing 737-800 – was built in 2016 and had its last scheduled maintenance on Monday.
There was no sign of any problems with the plane before take-off and the airline’s president said it had an “excellent, reliable crew”.
A statement from Boeing said its “heartfelt thoughts” were with all those affected following the “tragic event”.
There are several thousand Boeing 737-800s in operation around the world which have completed tens of millions of flights. They have been involved in 10 incidents, including this crash, where at least one passenger was killed, aviation safety analyst Todd Curtis told the BBC.
This is the first time a Ukraine International Airlines plane has been involved in a fatal crash.