Canadian Prime Minister Justin Trudeau says there is evidence to suggest the Ukrainian passenger jet which crashed in Tehran on Wednesday was hit by an Iranian surface-to-air missile, in what may have amounted to an “unintentional” strike.

Speaking to reporters in Ottawa, Trudeau said new intelligence regarding the crash of Ukraine International Airlines Flight 752 “reinforced the need for a thorough investigation into this matter.”

“The news will undoubtedly come as a further shock to the families who are already grieving in the face of this unspeakable tragedy,” he added.

Ukraine International Airlines Flight 752 crashed shortly after takeoff on Wednesday, killing all 176 people on board. CBC states most of the passengers were on the connecting flight en route to Canada, and 63 Canadian citizens were on board.

The tragedy occurred just hours after Iran launched missile strikes against two Iraqi military bases containing American troops, marking a drastic escalation in tensions.

In the hours after the crash, Ukraine’s embassy in Iran released a statement claiming the plane wasn’t brought down by a projectile or an on-board terror attack, but retracted that statement shortly afterwards.

The New York Times states that American officials have a “high level of confidence” the plane was destroyed by an Iranian surface-to-air missile.

However, BBC reports Iranian officials have reserved their judgment. Iranian state media initially suggested the crash may have been caused by a mechanical issue, and Ali Abedzadeh, head of the nation’s Civil Aviation Authority, said eyewitnesses saw the plane on fire before its crash.

“The issue of the missile’s impact on the aircraft cannot be true in any way,” he said.

Earlier, Abedzadeh said Iran would not hand the plane’s black box flight recorder to the United States or the jet’s American manufacturer, Boeing.

He today confirmed Iran would instead seek assistance from Ukrainian investigators to access the “damaged” recorder, and would potentially seek assistance from Swedish and Canadian authorities if required.

“Canada is working with its allies to ensure a thorough and credible investigation is conducted, to determine the causes of this fatal crash,” Trudeau said today.

“As I said yesterday, Canadians have questions, and they deserve answers.”

Image: Adrian Wyld / AP