Freightliner has announced it will lay off 1,120 workers at four North American manufacturing plants over the next three months. The company blamed continuing weakness in the North American heavy truck market for the layoffs.

"We regret this action is necessary," said Freightliner spokesman Chris Brandt in a released statement, "but this is one of the most difficult truck markets we've ever seen." Brandt said sales of heavy-duty and medium-duty trucks are off about 46 percent and 21 percent from a year ago.

The Mount Holly, NC, plant will lose 475 workers; the Kelowna, British Columbia plant will dismiss 180; the Santiago Tianguistenco, Mexico plant, 284; and the St. Thomas, Ontario plant, 181 workers.

The truck maker has already dismissed about 8,000 employees in previous rounds of layoffs since late 1999.