TORONTO - Hundreds of workers walked off the job at two doomed Ontario auto-parts plants on Monday to back demands for severance packages in the latest such labour action sparked by Canada's faltering manufacturing sector.

Members of the United Steelworkers union struck the Collins & Aikman plants, part of the Michigan-based company's plastics division, in Port Hope and Mississauga.

"It's a shame that our governments aren't doing a better job of keeping good manufacturing jobs in this province and in our country,'' said Marie Kelly, an assistant director with the union, said from the boardroom of the plant in Port Hope, Ont.

"It's also a shame that people have to walk off their jobs just to protect what's owed to them.''

The plant in Port Hope, which has 350 active employees and about 300 others on layoff, makes full instrument panels. The Mississauga plant, with 150 employees, makes interior trim such as cupholders and air vents.

Negotiations involving the union, senior lenders and the company were ongoing Monday in efforts to end the walkouts.

"We are engaged in a continuous dialogue with the union representatives and other interested parties,'' David Youngman, a company vice president, said from Southfield, Mich.

"We are optimistic that production will resume shortly without incident while we work toward reaching a mutually agreeable resolution in regards to the issues that led to this action.''

Collins & Aikman is selling or closing the 28 plastics plants it operates in the United States, Canada and Mexico as part of a 2005 bankruptcy filing.

The soft-trim division, which is under bankruptcy protection, has a plant in Kitchener, Ont.

The issue is bleaker for the plastics division and its two struck-hit plants, which the company has been trying to sell without success.

"As we've yet to solicit interest from potential buyers for these locations, we expect production to end at these facilities at some point during the fourth quarter,'' Youngman said.