Europe has urged airlines to avoid all Iranian airspace "until further notice" after Iran admitted its armed forces "unintentionally" shot down Ukraine International Airlines flight PS752, killing all 176 people aboard.
EU air safety regulator EASA advised carriers to avoid overflying the Islamic Republic, regardless of altitude, "as a precaution."
Iranian officials who had for days denied responsibility for Wednesday's disaster, admitted on Saturday it was caused by "human error".
Iranian President Hassan Rouhani tweeted on Saturday that the country "deeply regrets this disastrous mistake".
'I wished I was dead'
The armed forces said in a statement posted by Iranian state media that the plane came close to a sensitive military site and appeared to be a "hostile target". They said they were on a high threat alert due to increased enemy air traffic in the region.
Gen. Amir Ali Hajizadeh, the head of the Iranian Revolutionary Guard's aerospace division, said his unit accepted full responsibility for the shootdown. In an address broadcast by state TV, he said when he learned about the downing of the plane, “I wished I was dead.”
Iran's foreign minister Javad Zarif blamed "human error at a time of crisis caused by US adventurism". Rouhani, in his apology released by state media, also lamented an "atmosphere of intimidation and aggression by the American regime".
Flight PS752, which was bound for Kyiv, crashed shortly after takeoff from Tehran only hours after Iran launched missiles at U.S. forces amidst a rising escalation between the two countries.
The missile strike was in response to the US killing of the head of Iran's elite Quds Force General Qassem Soleimani.
US President Donald Trump said he had eliminated "the world's top terrorist" in a speech after Soleimani's death. Secretary of State Mike Pompeo said that there had been an "imminent threat" that included "attacks on US embassies".
Tensions between Iran and the US escalated in December after a US contractor was killed in a rocket attack on an Iraqi airbase, the Associated Press reported. The US retaliated in December by launching airstrikes targeting an Iran-backed militia.
Calls for an investigation
Ukrainian President Volodymyr Zelenskiy said that he expected Iran "to bring those responsible to justice, return the bodies, pay compensation and issue an official apology".
Zelenskiy called for the investigation to be "full, open & continue without delays or obstacles".
World leaders were quick to call for an investigation into the crash, with the EU calling for a "comprehensive and transparent investigation".
German Chancellor Angela Merkel called Iran's announcement a "big step" towards finding out what happened to PS752 and to discuss "consequences."
"Iran has announced that it was a big mistake," she said during a visit to Moscow. "So it's good that with that those responsible have been identified."
Canadian Prime Minister Justin Trudeau said on Saturday that Canada was concentrating on "closure, accountability, transparency, and justice for the families" after the disaster killed 53 Canadians.
He called the shootdown a national tragedy and said "all Canadians are mourning together.''