New information suggests an Iranian surface-to-air missile brought down a Ukrainian passenger plane that crashed near Tehran, Prime Minister Boris Johnson has said.
Four Britons were among the 176 people who died in the crash shortly after take-off on Wednesday, the PM said.
He added there was now “a body of information that the flight was shot down” by an Iranian missile.
“This may well have been unintentional,” Mr Johnson added.
Iran has ruled out a missile strike by its air defences as the cause of the crash, which came just hours after it carried out missile strikes on two airbases housing US forces in Iraq.
The air strikes were in retaliation for the US killing of top Iranian general Qasem Soleimani.
Mr Johnson added in a statement that the UK government was working closely with Canada and other international partners affected by the crash and that “there now needs to be a full, transparent investigation”.
“It is vital that there should be an immediate and respectful repatriation of those who’ve lost their lives to allow their families to grieve properly,” he said.
“The UK continues to call on all sides urgently to deescalate to reduce tensions in the region.”
It was previously reported that three British nationals had died in the crash.
The PM’s comments came after Canadian Prime Minister Justin Trudeau said he had seen evidence that suggested Iran’s missiles brought down the Boeing 737-800 – which was operating Ukrainian International Airlines flight PS752.