Iran has denied claims that Ukraine International Airlines flight PS752 was shot down outside Tehran by one of its missiles on Wednesday morning.
Western leaders, including Justin Trudeau, Donald Trump and Boris Johnson, suggested the passenger aircraft was brought down by surface-to-air missiles, an assertion refuted by Iran’s civil aviation chief.
New video appeared to show a plane being hit by a projectile over Tehran.
The Boeing 737-800 crash, which resulted in the loss of 176 lives, came just hours after Iran carried out missile strikes on two airbases housing US forces in Iraq.
US media have speculated that the airliner may have been mistaken for a warplane as Iran prepared for possible US retaliation.
Victims of the crash included 82 Iranians, 63 Canadians and 11 Ukrainians as well as nationals from Sweden, the UK, Afghanistan and Germany.
Iran has promised a full investigation. However, TV images from the crash site on Thursday showed a bulldozer helping to clear debris away, raising concerns that vital evidence could have been removed.
Meanwhile, the “black box” flight recorders recovered from the wreckage will be opened of Friday, Iran’s official Irna news agency reported.
At a news conference on Friday, Iran’s Civil Aviation Organisation (CAOI) chief Ali Abedzadeh repeated his view that a missile was not the cause of the crash.
“The thing that is clear to us and that we can say with certainty is that this plane was not hit by a missile,” he told reporters.
“As I said last night, this plane for more than one and a half minutes was on fire and was in the air, and the location shows that the pilot was attempting to return.”
On Thursday, government spokesman Ali Rabiei accused the US and its allies of “lying and engaging in psychological warfare” in their speculation over the cause of the accident.
An Iranian official told the BBC on Friday that there was documentation to prove that the plane had a mechanical issue before take-off. It was not signed off for flying, but Ukrainian airline officials had overruled these objections, the official said without giving further details.
Canadian Prime Minister Justin Trudeau said he had received intelligence from multiple sources indicating the plane was shot down by an Iranian surface-to-air missile, adding that it was possible that this was unintentional.
“This reinforces the need for a thorough investigation,” he said. “Canadians have questions and they deserve answers.”
But he said it was too early to apportion blame or draw any conclusions, and refused to go into detail about the evidence.