General Motors is asking an Ontario court to end a blockade at its Canadian headquarters and is seeking $1.5 million in compensation from the Canadian Auto Workers for damages that occurred at its assembly plant in Oshawa, Ont.

The union began its blockade of the Oshawa plant last Wednesday to protest the company's plans to shut down four North American assembly plants, including the one at its Canadian headquarters, which employs 2,600 people.

CAW Local 222 president Chris Buckley said he expected GM to go to court to end the blockade, but was surprised at the request for damages from the union and five of its members, including Buckley, since the plant has been in operation throughout the protest.

"I'd like to know where they get their numbers from because we've kept the two best assembly plants in the world operating," he said.

GM filed a notice of action in the Ontario Superior Court of Justice on Tuesday. The automaker said the protest, now in its eighth day, is hampering its Canadian operations and specifically pointed to loss of vehicle production last Saturday. The company alleges staff have been kept from work as a result of the blockade.

GM spokesman Stew Low said the company had no choice but to take legal action.

"We've been told repeatedly by the union since they put it up that the blockade would come down, but that hasn't happened," Low said.

"It's not our preferred course of action but, at this point, it's the only course of action that we see to be able to get our employees back into our building and continue working."

He wouldn't comment on details of the legal application or GM's bid for compensation.

Buckley and other CAW officials are meeting with union lawyers in Toronto on Wednesday.

With files from the Canadian Press