Reuters - Iran considers the passengers with dual nationality, who were on a Ukrainian plane that was shot down accidentally earlier this month, killing all on board, to be Iranian citizens, a Foreign Ministry spokesman said on Monday.

Many of the 176 who perished in the disaster were Iranians with dual citizenship, which is not recognized by Iran. Canada had 57 citizens on board.

�We have informed Canada that Tehran considers dual nationals who were killed in the plane crash as Iranian citizens ... Iran is mourning their deaths,� Foreign Ministry spokesman Abbas Mousavi told a televised weekly news conference.

Canadian Foreign Minister Francois-Philippe Champagne last Wednesday dismissed the Iranian position on dual nationality as �nonsense.� Prime Minister Justin Trudeau said on Friday the issue had not really come up because the Iranians recognized the importance of the families� wishes.

�So far, we have assurances from them (Iran) that this will happen,� a Canadian government official said on Monday, referring to the families� wishes being respected. �Of course, we will judge them on their actions.�

The official requested anonymity given the sensitivity of the situation.

As protests erupted in Iran after the plane disaster, the British ambassador in Tehran was briefly detained here Officials said he was at an "illegal" rally, while the envoy said he was attending a vigil for victims. Britain criticized his detention.

�Iran respects all foreign diplomats in Iran as long as they do not violate international laws,� Mousavi said in reference to the detention.

Writing by Parisa Hafezi, additional reporting by David Ljunggren in Ottawa; Editing by Edmund Blair and Bernadette Baum