By the end of the day on Monday, GM officials said the walkout by 3,400 United Auto Workers members at the Flint Metal Centre had so far affected 13,100 hourly workers at five assembly plants in the United States and Canada.

Plants where production was scaled back on Monday included the Orion Assembly Centre in Orion, Michigan; Fairfax Assembly in Kansas; Buick City in Flint; Moraine Assembly in Ohio; and Oshawa Ontario plant No 1 in Canada.The plants make mid-size and large cars across GM's line-up, such as the Oldsmobile Aurora, Eighty Eight, and Intrigue; the Buick Riviera and Park Avenue; Pontiac Grand Prix and Bonneville; and Chevrolet Lumina and Monte Carlo.

At Moraine, GM makes the Chevrolet Blazer, Oldsmobile Bravada and GMC Jimmy and Envoy compact sport utility vehicles.

There was somespeculation on Monday by industry analysts that GM may also curtail production soon at the Flint truck plant that makes commercial and medium-duty trucks. All the assembly operations rely on stamped steel parts such as hoods, doors, fenders and engine cradles from the Flint Metal Centre. Bargainers for GM and the UAW Local 659 were still talking late in the afternoon Monday in Flint, said GM spokeswoman Mary Irby. The two sides are at odds over staffing levels, work rules, new capital investment and other issues.

If the strike continues, at least 15 car and truck assembly plants could be idled, along with other parts facilities that feed those plants.

CS First Boston analyst Nicholas Colas said in a research note on Monday that the strike would affect at least eight truck plants by mid-week. Wall Street analysts estimate that GM could lose up to $200 million to $300 million a week in lost profits if the strike drags on long enough.

Although the Flint strike is expected to quickly affect GM's truckproduction, the automaker will try to shift some parts to higher-priority plants, such as its full-size sport utility vehicle factory in Janesville, Wiscosin said GM Truck Group spokesman Dan Flores. He added that GM's launch of its all-new 1999 model Chevrolet and GMC full-size pickup trucks in Oshawa, Ontario, remains unaffected by the strike. ``The timing of the production launch will be maintained,'' he said. In March 1996, a 17-day strike at two GM brake plants in Dayton shut down 26 of 29 North American assembly plants and cost the auto giant a total of $900 million.