CHATHAM, Ont. - Navistar International Corp. said Tuesday it's closing its truck manufacturing plant in Chatham, Ont., for good -- a move the Canadian Auto Workers union called a "devastating blow" to the 1,100 workers who have been out of work for at least two years.

The plant has been idle since 2009, and at the time 300 workers were handed pink slips, in addition to 800 who were already on lay off at the time.

The Warrenville, Ill.,-based company said in a statement it was unable to reach a collective bargaining agreement with the CAW, and that production in Chatham has already been absorbed by Navistar plants elsewhere.

Navistar also said it plans to significantly scale back operations at its headquarters and motor coach manufacturing plant in Oregon. One of its subsidiaries is also closing a plant in Indiana.

"We understand the impact these decisions have on our employees," said Dee Kapur, president of Navistar Truck Group. "We will treat people with respect and provide support to help them with their transitions."

The closure is "a devastating blow to the workers, their families and the entire community," CAW president Ken Lewenza said in a statement.

"Despite our relentless efforts since 2009 to reopen the idled facility and get our members back to work, Navistar has remained rigid and is now moving ahead with plans to shutter the plant," he said.

The plant has been in the Chatham community for more than 60 years, and had been one of the largest employers in the area, CAW said.

The union said it plans to meet with Navistar (NYSE:NAV) in the coming weeks in an attempt to bargain a fair closure agreement on behalf of its laid-off members.

"As is always the case when bargaining with Navistar, I'm expecting that these talks will be unnecessarily difficult and challenging," Lewenza said.

CAW said the Chatham closure is the latest in a long list of shutdowns in Ontario since 2002. It said the trend is a result of the high Canadian dollar, lax restrictions on capital mobility, corporate-friendly free trade deals and a lack of action by governments.

The North American truck industry has also been hit hard by the slumping economy and a drop in sales that has hit truck manufacturers hard.

Two years ago, the German-based Daimler AG medium- and heavy-duty truck maker announced the shutdown of its Sterling Truck assembly plant in St. Thomas, Ont., just south of London -- a move that affected 1,300 jobs.

Plants have also been cut in the United States and production shifted to other parts of the world.