The union had chosen the company as its second bargaining target after Ford, to address GM-specific issues in another round of contract talks.

Earlier last month, Unifor ratified a new three-year contract with Ford that offered wage increases of up to 25% to more than 5,600 workers at its Canadian facilities.

The major issues of contention include GM’s full-time temporary workers classification, the universal health allowance for retirees and future product investment commitments, the union said.

The union representing hourly workers in Canada faces an 11:59 p.m. ET deadline on Monday to reach a new deal with GM. Unifor represents about 4,300 workers at GM covered by these talks.

GM Canada did not immediately respond to a Reuters request for comment.

Unifor's talks with the Detroit Three automakers in Canada are separate from the United Auto Workers (UAW) union's coordinated action in the United States.

In the United States, UAW held off on additional strikes against Detroit Three auto plants on Friday, citing GM's unexpected willingness to allow workers at joint-venture battery plants to be covered by union contracts.

The Canadian operations of the Detroit Three are much smaller than their U.S. setups, but the three automakers each have critical factories in Canada.