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 Montreal Longshoremen's Union rejected the final offer made for a new labour contract, the Maritime Employers Association (MEA) said on Sunday. The MEA has no choice but to declare lockout as of 9 pm,

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