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.

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

Canada’s labor minister said Tuesday he is intervening to end lockouts at the country’s two biggest ports. Labor Minister Steven Mackinnon said the negotiations have reached an impasse and he is directing the Canada Industrial Relations Board to order the resumption of all operations at the ports and move the talks to binding arbitration.