MONTREAL (AP) _ Workers at three Montreal-area plants of Bombardier Aerospace went on strike Monday morning after rejecting the company's latest contract offer.

Work at the plants was paralyzed, halting production on the company's regional jets and the Challenger business jets.

The company employs about 7,400 workers at the plants.

The union had been seeking a 5 percent annual raise in a three-year contract, with a retirement age of 58 instead of 60 without penalty. Union members earn an average of $14 (U.S.) an hour.

Bombardier offered a salary increase of 3.25 percent in each year of a four-year contract, plus a $650 (U.S.) signing bonus.

Bombardier, a world leader in regional and business jet production, employs 58,000 people worldwide.