People pay their respect during a candlelight vigil to honor victims of the Ukrainian passenger plane crash at Mel Lastman Square in Toronto, Canada, Jan. 9, 2020. (Xinhua/Zou Zheng)

Canadian Prime Minister Justin Trudeau had phone talks with Iranian President Hassan Rouhani on Saturday after Iran admitted its missile "unintentionally" downing the Ukrainian plane, killing all 176 people on board, including 57 Canadians.

In a news conference on Saturday, Trudeau said he told Rouhani that Iran's admission was an important step in providing answers for families, but more must be done.

"A full and complete investigation must be conducted," Trudeau said. "We need full clarity on how such a horrific tragedy could have occurred."

In their conversation, Rouhani promised further investigation into the circumstances surrounding the plane crash.

Rouhani said that the investigation by the Iranian military found that the missiles that caused the downing of the plane were fired due to "human error."

He said Iran welcomes any international cooperation in the framework of international regulations to shed more light on the incident.

The plane crashed early Wednesday local time just minutes after it took off from Teheran Imam Khomeini Airport.

It happened hours after Iran launched a missile strike on two US military bases in Iraq after a US airstrike killed Iran's Major General Qassem Soleimani near Baghdad International Airport.