Canada's Trudeau demands 'accountability' from Iran following plane admission
He also demanded "transparency, and justice for the families and loved ones of the victims," of whom many were Canadian dual nationals.
"This is a national tragedy, and all Canadians are mourning together," Trudeau's office said in a statement.
Sixty-three of the victims were Canadian, all of them thought to also be nationals of Iran.
Trudeau on Thursday said multiple intelligence sources indicated that Iran had shot down the Boeing airliner, but it may have been unintentional.
The route from Iran to Canada via Kyiv was cheap and popular among Iranian-Canadians, including many students and academics returning home from the holidays.
Hundreds of mourners held a candle-light vigil on Thursday night in Toronto to remember the crash's victims.
At the vigil, people in Toronto - which has a large Iranian community - expressed anger and sadness over the tragedy.
Some attendees blamed US President Donald Trump, who last Friday ordered the killing of a top Iranian general in Iraq, sending tensions between Washington and Tehran soaring.
Iran retaliated Wednesday by firing a barrage of ballistic missiles at Iraqi military bases housing US troops. The airliner went down just hours later.
"They are all gone and we don't know why. It's the right of the community and everybody to know what happened exactly," said a 55-year-old man who gave his name as Sam.
In Toronto, an estimated 100,000 Canadians are of Iranian origin. It is one of the largest Iranian communities in North America, after Los Angeles. Officials figures say there were 210,000 Canadians of Iranian origin in 2016.
Some in the crowd at the Toronto vigil shouted "We want justice!"
Vigils were also held in Ottawa and Montreal. In the capital, Trudeau laid a wreath during a ceremony held outside Parliament.
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