Intelligence indicates that a passenger jet which crashed in Iran killing all 176 people on board was shot down – possibly accidentally – the British and Canadian prime ministers said on Thursday night.

The Kiev-bound Ukrainian International Airlines plane crashed shortly after take-off on Wednesday.

It happened just hours after Tehran launched its airstrike on US bases in Iraq in retaliation for the killing by an American drone last week of Iran’s top general Qasem Soleimani.

Four British nationals died, including 42-year-old former Aberdeen oil and gas engineer, Sam Zokaei.

Mr Zokaei, who had dual British-Iranian nationality and lived in Surrey, was holidaying in Iran.

The tragedy also claimed the lives of 63 Canadians, along with dozens of others who were due to fly on to Toronto from Kiev.

Boris Johnson said there was now a “body of information” that indicated the Tehran airliner crash was caused by an Iranian missile.

In a statement, the Prime Minister said: “This may well have been unintentional. We are working closely with Canada and our international partners and there now needs to be a full, transparent investigation.”

Mr Johnson also confirmed four Britons died in the plane crash, up from the earlier reports of three.

The Conservative Party leader said the Government was “providing support to their families at this most terrible time”.

Justin Trudeau, the Canadian Prime Minister, said the latest developments would come as a “further shock to the families who are already grieving”.

He said: “We have intelligence from multiple sources including our allies and our own intelligence.

“The evidence indicates that the plane was shot down by an Iranian surface-to-air missile.

“This may well have been unintentional.”

He added: “This reinforces the need for a thorough investigation. Canadians have questions and they deserve answers.”

Mr Trudeau’s remarks came after CBS News quoted Pentagon insiders as saying a satellite detected infrared “blips” of two missile launches, followed by another blip of an explosion.

The belief is the Ukrainian plane was hit by a Russian-made Tor missile. Iran has said it will not hand over the recovered black box flight recorders to Boeing, the plane’s manufacturer, or to the US.

Previously, the Iranian military had disputed suggestions the airliner was brought down by a missile; officials in Tehran blamed an engine fire.

The airline ruled out human error and the crew were not said to have made an emergency call. Donald Trump said he felt “something very terrible, very devastating” had happened.

Speaking from the White House, the US President explained: “I have my suspicions…It’s a tragic thing but someone could have made a mistake on the other side.

“It was flying in a pretty rough neighbourhood and somebody could have made a mistake.

“Some people say it was mechanical. I personally don’t think that’s even a question. So, we’ll see what happens.”

When asked if he thought the plane had been shot down by accident Mr Trump replied: “I don’t know, I really don’t know. That’s up to them, at some point they’ll release the black box. Ideally, they’d get it to Boeing but if they gave it to France or if they gave it to some other country that would be OK too…I have a feeling that something very terrible happened. Very devastating.”

Two US officials said it was “highly likely” that an Iranian anti-aircraft missile downed the Ukrainian jetliner.

They said they had no certain knowledge of Iranian intent but said it could have been a mistake and that the airliner was taken for a threat.

Flight PS752 fell from the sky in darkness just moments after it left Imam Khomeini International Airport in Tehran at just after 6am local time [2.40am GMT] on Wednesday.

The passengers also included 82 Iranians and 11 Ukrainians, including the crew of nine. The other two named Britons killed were Saeed Tahmasebi Khademasadi, from west London, and Mohammad Reza Kadkhoda Zadeh, from near Brighton.

Following the tragedy, several airlines rerouted flights away from Tehran’s airspace.

Mr Johnson pushed for the facts to be established in a phone-call with Volodymyr Zelenskyy, the Ukrainian President.

A Downing Street spokesman said: “The Prime Minister spoke to President Zelenskyy of Ukraine this afternoon. He offered his condolences to the President for the loss of the Ukraine International Airlines plane and for all those who were on board.

“President Zelenskyy updated the Prime Minister on Ukrainian efforts to establish the facts and the Prime Minister offered UK support. He said that there needed to be a full, credible and transparent investigation into what happened.”

Asked if there were any concerns about the cause of the disaster, the spokesman added: “I’m not going to speculate on this but the reports we have seen are very concerning and we are urgently looking into them.”

Earlier, Mr Johnson called for an end to hostilities in the Persian Gulf in a phone-call with Hassan Rouhani, the Iranian President.

The PM also made clear he remained committed to the nuclear deal with Tehran despite Mr Trump’s call for the UK to break away from the arrangement.

During the 20-minute call, Mr Johnson also urged an end to the “detention and mistreatment” of Nazanin ZaghariRatcliffe, the jailed British-Iranian mother, and other dual nationals held by Tehran, and demanded their immediate release.

Downing Street said he “underlined the UK’s continued commitment” to the troubled nuclear deal in the conversation.

On Wednesday, the US President  insisted the “time has come” for Britain, Germany, France, Russia and China to “break away” from the Joint Comprehensive Plan of Action [JCPOA]; America has already pulled out of the agreement which was aimed at easing sanctions in exchange for Iran not pursuing a nuclear weapon.

The PM’s spokesman said: “The JCPOA is the best arrangement currently available to deliver upon our goal of stopping Iran having a nuclear weapon.”

Dominic Raab, the Foreign Secretary, who held talks in Washington with Mike Pompeo, his US counterpart, acknowledged that Iran’s breaches of the JCPOA were becoming “acute”.

“We want to see Iran come back to full compliance and we will be looking at all measures including potentially triggering the DRM (the deal’s dispute resolution mechanism),” he said.

Mr Johnson’s call with Mr Rouhani came as tensions appeared to have eased following Tehran’s retaliation against the US over the killing of General Soleimani.

In the Commons on Wednesday, Mr Johnson said General Soleimani “had the blood of British troops on his hands”. Following a missile barrage aimed at military bases in Iraq hosting US forces and troops from allies including the UK, Mr Trump suggested Tehran was “standing down”.

Labour’s Emily Thornberry noted how Washington had yet to produce evidence to justify the attack on General Soleimani.