World reacts to Iran's admission it downed Ukrainian plane
President Hassan Rouhani said a military probe into the tragedy had found "missiles fired due to human error" brought down the Boeing 737, calling it an "unforgivable mistake".
Supreme leader Ayatollah Ali Khamenei, who had reportedly learned the outcome of the investigation on Friday, offered his condolences and ordered the armed forces to address "shortcomings" so that such a disaster does not happen again.
Iran’s Revolutionary Guards Brigadier General Amirali Hajizadeh pinned the disaster on one individual, saying the missile operator acted independently when he shot down the Boeing 737 after mistaking it for a "cruise missile".
"He had 10 seconds to decide. He could have decided to strike or not to strike and under such circumstances he took the wrong decision."
"It was a short-range missile that exploded next to the plane," he added.
However the aerospace commander of the Revolutionary Guards accepted full responsibility.
For three days, officials in Iran had categorically denied Western claims that the Ukraine International Airlines (UIA) airliner had been struck by a missile in a catastrophic error.
As Iran scrambles to address the disaster, world powers are demanding accountability, transparency and justice for the tragedy which saw nationals from Iran, Canada, Ukraine, Sweden, Afghanistan, UK and Germany lost their lives.
Ukraine: 'Bring the guilty to the courts'
Ukrainian President Volodymyr Zelensky demanded Iran punish those responsible for the downing of the plane and pay compensation.
"We expect Iran... to bring the guilty to the courts," he wrote on Facebook.
"We hope the inquiry will be pursued without deliberate delay and without obstruction," Zelensky added
He urged "total access" to the full inquiry for 45 Ukrainian experts, and in a tweet also sought an "official apology".
Zelensky was to have a phone conversation with Iranian counterpart Hassan Rouhani later Saturday, according to the presidential press office.
Eleven Ukrainians were killed in the disaster, including nine crew members.
UIA chief Yevhenii Dykhne posted on Facebook, saying: "We never had any doubt that our crew and our plane could be the cause of this terrible catastrophe. They were the best."
Canada: 'Transparency and justice'
Canadian Prime Minister Justin Trudeau called for closure and accountability now that Iran had admitted downing the plane.
Trudeau demanded "transparency, and justice for the families and loved ones of the victims".
"This is a national tragedy, and all Canadians are mourning together."
Sixty-three of the victims were Canadian, all of them thought to also be nationals of Iran.
Vigils for the victims were held in cities across the country on Friday night. Trudeau laid a wreath during a ceremony held outside Parliament in the capital, Ottawa.
Russia: 'Iran must learn lessons'
Iran must "learn lessons" from the disaster, the chairman of the Russian parliament's foreign affairs committee said on Saturday morning.
"If decryption of the black boxes and the work of the investigation do not prove that the Iranian army did this intentionally, and there are no logical reasons for this, the incident must be closed.
"Hoping that lessons will be learned and action taken by all parties," said Konstantin Kosachev, quoted by the Interfax news agency.
Russian officials had previously cast doubt on US accusations an Iranian missile shot down the plane.
France: 'End escalation'
French Defence Minister Florence Parly said it was "important to seize this moment to give space to discussions and negotiations" on the Iran nuclear deal.
"The lessons that we should learn from the dramatic sequence of events that we have experienced... is that we must put an end to this escalation," Parly told France Inter radio.
She reiterated the French position that everything must be done to salvage the landmark 2015 nuclear accord with Iran, which US President Donald Trump withdrew from in 2018.
Germany: 'Draw the right consequences'
German Foreign Minister Heiko Maas said "it was important that Iran brought clarity to this issue.
"Now Tehran needs to draw the right consequences in the continued appraisal of this dreadful catastrophe, and take measures to ensure that something like this cannot happen again," Mass told Funke media.
Sweden: 'Complete and transparent' probe
Prime Minister Stefan Lofven said the "act should be condemned and Iran should assume all responsibility, including for the all persons affected.
"Iran said the plane was shot down in error. This declaration constitutes the basis for a complete and transparent investigation which should shed light on all the circumstances surrounding the incident," a statement said.
"We demand that Iran cooperates freely in the investigation and that the countries affected are allowed to participate using their national competencies and are fully informed about the investigation," he said.
Foreign Minister Ann Linde tweeted that "the downing of a civilian plane even if it's not intentional must be condemned. We want Iran to fully cooperate in the investigation."
The disaster came as tensions soared in the region after the US assassinated Iran's top general Qasem Soleimani' in a drone strike, which sparked fears of an all-out war between the two arch-nemeses.
"Human error at time of crisis caused by US adventurism led to disaster," Iranian Foreign Minister Mohammad Javad Zarif tweeted on Saturday.
"Our profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations," he added.
Washington said the Soleimani strike was carried out to prevent "imminent", large-scale attacks on American embassies, however analysts have disputed this claim.
Tehran had vowed "severe revenge" for the killing of Soleimani before launching missiles at the bases in Iraq.
Iran has invited the United States, Ukraine, Canada and others to join the crash investigation.
It is Iran's worst civil aviation disaster since 1988 when the US military said it shot down an Iran Air plane over the Gulf by mistake, killing all 290 people on board.
Video footage of the UIA 737, which The New York Times said it had verified, emerged and appeared to show the moment the airliner was hit.
A fast-moving object is seen rising at an angle into the sky before a bright flash appears, which dims and then continues moving forward. Several seconds later, an explosion is heard and the sky lights up.
Many airlines from around the world cancelled flights to and from Iran in the wake of the crash, or rerouted flights away from Iranian airspace.
Nations around the world have called for restraint and de-escalation, and fears of a full-blown conflict have subsided after US President Donald Trump said Iran appeared to be standing down after targeting the US bases in Iraq.