Canada's ruling Liberal Party lost a once-safe seat in a Montreal parliamentary constituency, preliminary results showed on Tuesday, a result likely to put more pressure on Prime Minister Justin Trudeau to quit.

The prime minister has faced calls to resign as party leader, including from within his own party. But he has insisted he plans to stay on and lead the party into the next electio

The loss, coupled with a recent Toronto defeat, signals waning support for Trudeau, who faces a challenging re-election campaign.

Canadian Prime Minister Justin Trudeau's ruling Liberals, trailing badly in the polls, face a struggle on Monday to retain a once-safe seat in a special election where failure to win could boost calls for a new party leader.