A Ukraine airliner that crashed in Iran, killing all 176 people aboard, was most likely brought down accidentally by Iranian air defences, US officials said on Thursday, and President Donald Trump said he did not believe the crash was due to a mechanical issue.

Citing an extensive review of satellite data, one US official said the government had concluded with a high degree of certainty that anti-aircraft missiles brought down the plane, on the same day that Iran launched ballistic missiles at US forces in Iraq.

The official said the Ukraine International Airlines plane had been tracked by Iranian radar.

The data showed the Boeing 737-800 was airborne for two minutes after departing Tehran when the heat signatures of two surface-to-air missiles were detected, one of the officials said.

That was quickly followed by an explosion in the vicinity of the plane, this official said. Heat signature data then showed the plane on fire as it went down. The flight was on its way to Kiev carrying mostly Iranians and Iranian-Canadians.

The crash happened early on Wednesday morning, hours after Iran launched missile attacks on US-led forces in Iraq, leading some to speculate that the plane may have been hit.

Iran’s head of civil aviation denied the reports as “illogical rumours”.

“Scientifically, it is impossible that a missile hit the Ukrainian plane, and such rumours are illogical,” the semi-official Isna News Agency quoted Ali Abedzadeh as saying.

Two U.S. officials said Washington believed the downing of the plane was accidental.

Speaking to reporters at the White House, Trump said he had a terrible feeling about the downed airliner but offered no details. He said he did not believe it was a mechanical issue.

“It’s a tragic thing. But somebody could have made a mistake — on the other side,” Trump said.

Ukraine had outlined four potential scenarios to explain the crash, including a missile strike and terrorism. Kiev said its investigators wanted to search the crash site for possible debris of a Russian-made missile used by Iran’s military.

Investigations into airliner crashes require regulators, experts and companies across several international jurisdictions to work together. It can take months to fully determine the cause and issuing an initial report within 24 hours is rare.

Canadian foreign minister Francois-Philippe Champagne called his Iranian counterpart to stress that Canadian officials needed “to be quickly granted access to Iran to provide consular services, help with identification of the deceased and take part in the investigation of the crash”.

“Canada and Canadians have many questions which will need to be answered,” a Canadian statement said.

Britain wants a transparent investigation, Prime Minister Boris Johnson’s spokesman said on Thursday following a call between the British leader and Ukraine President Volodymyr Zelenskiy.

“The Prime Minister said that there needed to be a full credible and transparent investigation into what happened,” the spokesman said.

Tensions between Washington and Tehran have risen with the US killing of a top Iranian general on Friday.

The Ukrainian airliner took off at 6.12am (local time) and was given permission to climb to 26,000 feet, Iran’s report said. It crashed six minutes later near the town of Sabashahr.

Bodies and body parts recovered from the site of the crash were taken to the coroner’s office for identification, the report said. Smouldering debris, including shoes and clothes, was strewn across a field where the plane crashed.