IRANIAN officials have denied claims that Iran shot down a Ukrainian passenger jet which crashed shortly after take-off in Tehran on Wednesday.

Initial reports suggested a technical failure led to the incident, which killed all 176 board.

But soon afterwards Western leaders, led by Canadian Prime Minister Justin Trudeau, insisted they had evidence that it had actually been downed by Iranian missiles.

Mr Trudeau claimed to have received intelligence reports that it had been hit by a surface-to-air missile launched in Tehran, although indicated it may have been unintentional.

It is thought 67 Canadians were on board the plane when it crashed minutes after take-off from Khomeini International airport.

“This reinforces the need for a thorough investigation,” the Liberal leader said, adding: “Canadians have questions and they deserve answers.”

This has been seized upon by other powers, including Britain and the US, where officials said they were “confident that Iran shot down a Ukrainian jetliner.”

It was a swift about-turn from initial Canadian intelligence reports which said: “The initial assessment of Western intelligence agencies is that the plane was not brought down by a missile. There is no evidence to suggest that,” adding a “technical malfunction” was most likely.

Suggestions that it was a Russian missile that struck the plane heightened fears that the accusation amounted to a co-ordinated propaganda exercise.

Iran has denied the accusations, with its civil aviation chief saying it was almost certain that the plane was not hit by a missile.

Government spokesman Ali Rabiei accused the US of “lying and engaging in psychological warfare” over the incident.

Iranian officials said they had documentation showing the plane had a mechanical issue and had not been cleared for take-off, although Ukrainian airline officials had overruled these objections.

The black box was due to be opened today and investigations into the cause of the crash are continuing.