Auto giant General Motors has told the union representing nearly 3,000 striking autoworkers that the company is ramping up production of the Chevrolet Equinox at two plants in Mexico, Unifor's national president Jerry Dias, says.

The news comes three weeks after Unifor workers hit the picket line at GM's CAMI plant in Ingersoll, fighting mainly for assurances from the company that the Ontario facility be designated the main producer of the popular SUV.

"That's the equivalent while we're in NAFTA negotiations of telling Canada that they're declaring war," said Dias.

The two Mexican plants will build the SUV for the North American market, Dias said from Washington, where he's attending NAFTA talks.

"This is about autoworkers in Mexico making $2 an hour [and] the movement of good paying middle-class jobs to Mexico," he said.

A 'threat' to the CAMI plant

Dias said GM's plan will have a direct impact on the CAMI plant.

"This has always been about [GM] ramping up production of the Equinox in Mexico and leaving our plant behind. That's their plan and how it's starting to unfold. The facts are that we need to solidfy the footprint in Ingersoll or there may not be a plant [there] in the long term," Dias told CBC's London Morning.

The Unifor president said it's an issue for the international labour movement.

"This is General Motors dropping the gauntlet on autoworkers in Canada and the United States and saying 'we're going to be sourcing your jobs to Mexico and there's not a damn thing you can do about it'. Well, there's a lot we can do about it."

When asked what specifically could be done, Dias replied: "General Motors declared war on Canada, so we're obviously not going to take it sitting down. We're going to do what we need to do to get their attention." He didn't elaborate.

Unifor president Jerry Dias addresses a strike rally at the CAMI auto plant in September. (Hala Ghonaim/CBC News)

The news also means the strike at CAMI, now nearly four weeks old, will go on longer than anybody anticipated, Dias said.

"They said they're going to satisfy the North American market through their Mexican operations. In other words, the strike that's going on right now at CAMI is going to continue. And I'm not sure when things are going to end," he said.

CAMI strike victim of bad timing: auto analyst

NAFTA negotiations and "America first" trade policies may have contributed to drawing out the strike and causing GM to take a harder line, said Tony Faria, director of the Office of Automotive and Vehicle Research at the University of Windsor in Ontario.

"What Unifor is demanding is maybe the straw that broke the camel's back. [GM could be saying] 'We can't do this. We can't agree to investments, jobs, and everything else for the next five, 10 years down the road when we don't know the size of the road, we don't know if there's going to be a NAFTA five, 10 years from now,'" Faria said.

"It was a gamble on the part of Unifor and a gamble they decided to take, and I'm sure that Unifor is a little upset that GM is taking, it looks like, a harder stand than Unifor expected.

"The auto companies have been setting up their supply chains for over 20 years now with the idea that there is a NAFTA and we can move parts and vehicles all around North America duty free. If NAFTA disappears, that's going to be a real crimp to the auto companies."

There is still "tremendous support" on the picket line, said Dan Borthwick, president of Unifor Local 88, which represents the Ingersoll workers.

CBC News has contacted GM Canada for comment.