Video report by ITV News Senior International Correspondent John Irvine
Iran has admitted its military "unintentionally" shot down the Ukraine passenger plane over Tehran which killed all 176 on board.
The Iranian government had previously repeatedly denied Western accusations they were responsible however, in the face of mounting evidence it acknowledged it had it shot down the Ukrainian jetliner by accident.
The plane, en route to the Ukrainian capital of Kyiv, was carrying 167 passengers and nine crew members from several countries, including 82 Iranians, 57 Canadians and 11 Ukrainians, according to officials.
Canadian prime minister Justin Trudeau said he was "outraged and furious" by the admission and said his country "will not rest until we get the accountability, justice and closure that the families deserve".
Trudeau said he spoke with Iranian President Hassan Rouhani on Saturday and told him the admission was "an important step towards providing answers for families".
The plane was shot down early on Wednesday, hours after Iran launched a ballistic missile attack on two military bases housing US troops in Iraq in retaliation for the killing of Iranian General Qassem Soleimani in an American airstrike in Baghdad.
No-one was wounded in the attack on the bases.
Iran's supreme leader Ayatollah Ali Khamenei expressed his "deep sympathy" for the victims and called for an investigation into the tragic incident.
A military statement carried by state media said the plane was mistaken for a “hostile target” after it turned towards a “sensitive military centre” of the Revolutionary Guard.
The military was at its “highest level of readiness,” it said, amid the heightened tensions with the US.
“In such a condition, because of human error and in an unintentional way, the flight was hit,” the military said. It apologised and said it would upgrade its systems to prevent future tragedies.
It also said those responsible for the strike on the plane would be prosecuted.
Iran’s acknowledgement of responsibility for the crash was likely to inflame public sentiment against authorities after Iranians had rallied around their leaders after Gen Soleimani’s killing.
But the majority of the plane crash victims were Iranians or Iranian-Canadians, and the crash came just weeks after authorities quashed nationwide protests ignited by a rise in petrol prices.
Footage shows the aftermath of the plane crash near Tehran
Iran’s President Hassan Rouhani blamed the tragedy on “threats and bullying” by the US after the killing of Gen Soleimani.
He expressed condolences to families of the victims, and he called for a “full investigation” and the prosecution of those responsible.
“A sad day,” Iran’s Foreign Minister Mohammad Javad Zarif tweeted. “Human error at time of crisis caused by US adventurism led to disaster. Our profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations.”
Boris Johnson said Iran's admission it shot down a passenger plane by mistake "reinforces the importance of de-escalating tensions in the region".
In a statement, the Prime Minister said: "Iran's admission that Ukraine International Airlines Flight 752 was shot down by mistake by its own armed forces is an important first step.
"This will be an incredibly difficult time for all those families who lost loved ones in such tragic circumstances. We will do everything we can to support the families of the four British victims and ensure they get the answers and closure they deserve.
"We now need a comprehensive, transparent and independent international investigation and the repatriation of those who died. The UK will work closely with Canada, Ukraine and our other international partners affected by this accident to ensure this happens.
"This tragic accident only reinforces the importance of de-escalating tensions in the region. We can all see very clearly that further conflict will only lead to more loss and tragedy. It is vital that all leaders now pursue a diplomatic way forward."
Ukraine’s president said Iran must take further steps, including an official apology, following the admission.
Volodymyr Zelenskiy said that his country expected “assurances” from Iran of a “full and open investigation, bringing the perpetrators to justice”.
He added that Ukraine expected the “paying of compensation” and “official apologies through diplomatic channels”.
He also expressed hope for the continuation of the crash investigation without delay. A team of Ukrainian investigators is already in Iran.
“Our 45 specialists should get full access and cooperation to establish justice,” he said.
The jetliner, a Boeing 737 operated by Ukrainian International Airlines, went down on the outskirts of Tehran shortly after taking off from Imam Khomeini International Airport.
Iran had denied for several days that a missile caused the crash. But then the US and Canada, citing intelligence, said they believed Iran shot down the aircraft with a surface-to-air missile, a conclusion supported by videos of the incident.
“This is the right step for the Iranian government to admit responsibility, and it gives people a step toward closure with this admission,” said Payman Parseyan, a prominent Iranian-Canadian in western Canada who lost a number of friends in the crash.
“I think the investigation would have disclosed it whether they admitted it or not. This will give them an opportunity to save face.”