Members of the union representing about 1,200 dockworkers at the Port of Montreal rejected by 99.7 per cent the offer proposed by the employer on Sunday, making a lockout likely. A spokesperson for the Canadian Union of Public Employees said 1,086 of its 1,197 members exercised their right to vote following a general meeting on Sunday.

The Montreal Longshoremen's Union rejected a final offer made for a new labour contract, leading to a lockout being declared, the Maritime Employers Association (MEA) and the union said on Sunday.

Longshoring activity at the Port of Montreal is set to grind to a halt as an employers’ group locks out 1,200 union members.

The employers' association at the Port of Montreal has issued the dockworkers' union a "final, comprehensive offer," threatening to lock out workers at 9 p.m. Sunday if a deal isn't reached.

The dispute exacerbates the disruption to trade in Canada as a lockout at ports along the West Coast continues.