A lockout at the Port of Montreal began Sunday night. The CEO of the Montreal Port Authority says if the dispute between dockworkers and the Maritime Employers' Association drags on, it will have disastrous consequences for the economy.

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.