Canada and several other countries with nationals killed in the shootdown of a civilian airliner called on Tehran Sunday to abide by its international commitments after Iranian authorities briefly arrested the British ambassador.

"We call on Iran to uphold the Vienna Convention," Canada's foreign ministry said, referring to a 1961 international treaty that sets out protections from harassment for foreign diplomats.

Canada issued the statement after a call among representatives of countries whose citizens were among the 176 people killed when a Ukrainian airliner was hit by an Iranian missile January 8.

The group formed by Canada in the wake of the disaster includes Britain, Ukraine, Sweden and Afghanistan.

"All countries on the call noted their concern that the British ambassador to Tehran was temporarily detained by Iranian officials following his attendance at a vigil for the victims of flight PS752," the statement said.

Iran earlier Sunday confirmed it briefly arrested Rob Macaire, the British ambassador, for attending an "illegal gathering" - a charge he has denied.

The European Union and France criticized Tehran for the arrest as well.

On Saturday, Canadian Prime Minister Justin Trudeau said he was "outraged and furious" over the shootdown, demanding a full investigation and for Tehran to assume responsibility for the tragedy, including financial compensation.

Iran's leaders admitted on Saturday that Iranian forces accidentally shot down the airliner after mistaking it for a cruise missile.

Trudeau is expected in Edmonton, Alberta Sunday to attend a memorial service for the 57 Canadian victims of the disaster. About a dozen were from Edmonton.

The prime minister, who will be accompanied by Foreign Minister Francois-Philippe Champagne, is expected to speak at the event.