General Motors Canada says it is suing the Canadian Auto Workers Union for $1.5 million because a week-long blockade has disrupted its business and has caused the company to lose revenue.

The CAW says it was expecting a legal injunction to end the member-led blockade but the union was shocked when they found out it was being sued for compensation.

Nonetheless, news of the suit did not dissuade protesters from fighting for the cause.

On Wednesday, one GM employee was turned away when he showed up for work in his BMW. Protesters told him cars made outside of Canada were not being allowed on the premises.

"I'll tell you what, you turn around and when you come back in one, we'll talk then," one protester said to the man behind the wheel.

Protesters have formed a blockade around GM's Canadian headquarters in Oshawa since June 4, preventing managers from accessing the building.

Union members began demonstrating when GM announced it would close the Oshawa plant in 2009, effectively laying off 2,600 people.

GM announced the closure just two weeks after negotiating a contract with the union. The company's plan for the plant was not mentioned during contract talks, union officials said.

On Tuesday, the auto industry giant filed a notice of action in Ontario's Supreme Court of Justice to force an end to the blockade. The suit seeks damages from the union local and five of its members, including Chris Buckley, president of CAW Local 222.

CAW officials are meeting with union lawyers in Toronto Wednesday morning to discuss their options.

Buckley said GM's legal action will not deter protesters from fighting to keep the Oshawa plant open.

Buckley said if the union is ordered to remove the blockade, members will simply move their protest elsewhere.

The demonstration will remain peaceful, Buckley said.

Meanwhile, support for CAW members is growing across the province. On Wednesday the Ontario Secondary School Teachers' Federation and CUPE representatives attended the blockade and stood side by side with protesters.

"This is important -- solidarity is important," said Mike Platt with the OSSTF.

Paul Moist, the national president of CUPE, told the crowd GM's actions set a dangerous precedent.

"If General Motors can repudiate a collective agreement that they've signed with their work force -- the ink's not dry on it - and violate that agreement, there isn't a collective agreement safe in Canada," Moist said.

"It's not a CAW issue, it's an issue for all workers in Canada," he said.

The CAW is planning a massive rally on Thursday. They are expecting about 10,000 people to come out and show their support.

Talks underway for third car line

Meanwhile, Economic Development and Trade Minister Sandra Pupatello said Wednesday that GM and the Ontario government are in discussions about adding a third car line at the automaker's troubled Oshawa plant.

Pupatello told reporters the talks are taking place at a very "high level."

"We do want to talk about what's next for General Motors so we're determined as best we can to try to get detail, a little meat on the bones of some of the conversation," she said.

"We're trying to nail down timing, because if in fact we have an opportunity for a new car product, there is still going to be a couple of years where we have a gap between the estimated date of closure of the truck plant and a launch of a new vehicle."

The minister said once the preliminary discussions are complete, the next conversation would be with "people who are responsible for North American manufacturing where some of the decision-making actually takes place."

With a report from CTV Toronto's Dana Levenson and files from The Canadian Press