Canadian autoworkers employed by General Motors at a key assembly plant in Ontario went on strike on Monday after GM and negotiators from Unifor Local 88 failed to reach a deal on a new contract covering some 3,000 workers.

The strike shuts down production at a plant that builds one of GM's most popular vehicles, the Chevrolet Equinox utility vehicle. GM is in the midst of ramping up production of Equinox for the 2018 model year and inventories of the new vehicle are in relatively short supply.

Dan Bothwick, president of Unifor Local 88, posted a message on the Local's website only moments calling for the strike, only moments before the old contract expired late Sunday.

The strike involves a long running battle between Unifor and GM over the company's decision to move work, previously done at the CAMI plant in Ingersoll, to a plant in Mexico.

Some 600 workers were idled last month when GM shifted production of a second vehicle, the GMC Terrain utility vehicle to a GM plant to Mexico where labor cost are cheaper than they are in Canada.

"We built the Terrain and the Equinox, and they moved the Terrain to Mexico despite being number one in quality and having massive sales, so part of our demands are to (ensure) the Equinox stays in Ingersoll, but General Motors is not interested in that whatsoever," says Unifor Local 88 chair Mike Van Boekel told the London (Ontario) Free Press a meeting earlier in the day in Ingersoll with the members of Unifor Local 88

"We've gone back and forth on a few different proposals over the course of these few weeks, but quite honestly, we are light years apart from each other in terms of reaching an agreement," Van Boekel said.

GM said in a statement e-mailed after the strike began that is was disappointed the negotiations had failed to produce a new agreement.

"While General Motors of Canada and our Unifor partners have made very positive progress on several issues over the past weeks, the Company is disappointed that we were not able to complete a new agreement.  We encourage Unifor to resume negotiations and to continue working together to secure a competitive agreement."

The movement of work from Ingersoll to Mexico also has prompted Unifor to put pressure on the Canadian government of Justin Trudeau to demand greater protection for workers in any proposed changes to the North American Free Trade Agreement. Representatives of Mexico, Canada and the United States recently opened discussions on NAFTA at the urging of the Trump administration.

GM and other automakers, which have poured billions of dollar of investment into Mexico since the recession, have said the prefer the status quo to any major changes to what they view as a successful agreement that has helped protect jobs in all three countries.