Iran’s admission it “unintentionally” shot down a Ukrainian passenger jet has sparked demands for justice for the 176 people on board who were killed.
The calls were led by Ukraine’s president and the prime minister of Canada, which lost 57 nationals.
Social media footage has shown protests in Iran, some of them calling for Supreme Leader Ali Khamenei to resign.
The plane was shot down on Wednesday, hours after Iran had struck two air bases housing US forces in Iraq.
Those missile strikes were Iran’s response to the US killing of senior Iranian commander Qasem Soleimani. He died in a drone strike in Baghdad on 3 January.
Iran had initially denied reports its missiles had brought down the plane, with one spokesman accusing Western nations of “lying and engaging in psychological warfare”.
Ukraine International Airlines flight PS752, en route to Kyiv, came down near Imam Khomeini Airport in Tehran shortly after take-off. Victims included dozens of Iranians and Canadians, as well as nationals from Ukraine, the UK, Afghanistan and Germany.
Ukrainian President Volodomyr Zelensky has demanded Iran “bring the guilty to the courts”, repatriate the remains of the victims, pay compensation, give total access to Ukrainian officials and issue an apology through diplomatic channels.
He later spoke with Iranian President Hassan Rouhani and said he had been assured that “all persons involved in this air disaster will be brought to justice”.
Canadian Prime Minister Justin Trudeau also spoke with the Iranian president.
Mr Trudeau said he was “outraged and furious” and had told Mr Rouhani that there must be a full investigation with “full clarity on how such a horrific tragedy could have occurred”.
Mr Trudeau said: “Canada will not rest until we get the accountability, justice and closure the families deserve… they are hurt, angry and grieving and they want answers.”
He said Mr Rouhani had made a commitment to de-escalation and added that Canadian crash investigators were due to arrive in Tehran shortly.