General Motors is moving production of the Chevrolet Camaro from its Oshawa, Ont., plant to a Michigan facility, the company said in a statement denounced by the Canadian Auto Workers’ union as a “betrayal.”

GM said Wednesday that "lower capital investment and improved production efficiencies were key factors" in the move.

But CAW president Ken Lewenza said the automaker’s decision is “a betrayal of the commitment made to the Canadian government, to Canadian taxpayers.”

“It’s a betrayal to our CAW membership and it’s a betrayal to Canada relative to Canadian jobs in a very important industry in the province of Ontario,” he said at a news conference in Oshawa.

However, the CAW’s latest contract with GM guaranteed Camaro production at the Oshawa flex plant only until the end of the current generation. GM said production of the new Camaro will be consolidated with the production of the Cadillac CTS and ATS in Michigan because they are all rear-wheel drive vehicles and rolling them out from the same facility will improve efficiency.

The CAW said the move will cut production in Oshawa by as much as one third starting in late 2015 or early 2016. The union said it doesn’t know exactly how many jobs will be lost as a result, but warned that auto parts companies in the region could also be affected.

“We are obviously very much frustrated today,” Lewenza said, adding that he has already spoken to Prime Minister Stephen Harper’s chief of staff and Ontario Premier Dalton McGuinty about the issue.

“I asked (McGuinty) to use all of his political will to talk to General Motors about this very terrible decision,” he said, calling on GM to replace 100,000 vehicles a year worth of production once the Camaro is gone.

Federal Finance Minister Jim Flaherty said Wednesday that GM remains committed to the Oshawa flex plant, which employs about 2,000 people.

“I haven’t heard a word about job losses, I can tell you that. So I think if anyone is presuming that there will be job losses two and a half years from now, I think that’s a huge presumption,” he said.

The most recent labour deal between CAW and GM includes a commitment to create or maintain 1,750 jobs.

GM invested $740 million in 2006 to build a flexible assembly line at its Oshawa operation, where it will produce the new versions of the Cadillac XTS and the Chevrolet Impala. The company has said that it will add a third shift in Oshawa to build the Impala.

Ottawa and Ontario contributed $13.7 billion to help bail out GM and Chrysler more than three years ago and own about nine per cent of GM's common shares.

With files from The Canadian Press