TORONTO (Reuters) - Angry autoworkers blockaded the entrance to General Motors of Canada headquarters in Oshawa, Ontario yesterday, one day after General Motors (GM) said it would shut its Oshawa truck plant.

"We're not allowing any GM of Canada employees to enter the headquarters building," said Chris Buckley, of the Canadian Auto Workers union, which says 2,600 jobs will go if the truck plant closes.

"We are going to stay here until General Motors reverses the decision they made yesterday, or at the very least commits to a product for the Oshawa truck plant, or sits down face-to-face with this union to try to explain why they have broken our brand new agreement."

TV pictures showed some 100 autoworkers on a road leading to the Oshawa plant, which is to be closed as GM tries to shore up a restructuring plan that has been overtaken by a steep decline in US sales of pickup trucks and SUVs in the face of surging gas prices and tighter credit.

Two plants in the US and one in Mexico are also slated to close.

The CAW says the closure of the Oshawa plant is a betrayal. GM and the CAW signed a new three-year collective bargaining agreement on May 15 that included a wage freeze and GM promises to boost production in Canada rather than cut it. Under that deal, GM said it would start producing hybrid versions of two of its trucks at the Oshawa plant.

The plant currently produces the Chevrolet Silverado and the GMC Sierra crew-cab and extended-cab pickup trucks, which GM Canada spokesman Stew Low said are taking the biggest hit of GM's products in the US.

He said the hybrid versions of the Silverado and Sierra would still be built and rolled out at the end of the year, but at other plants, either in the US or in Mexico.

"Our main customer is the US and there is a huge and very drastic shift away from trucks and SUVs and we have to react to that because we can't continue to buy vehicles that people aren't buying," Mr. Low said.