FLINT, Mich. (AP) _ General Motors Corp. is closing its Buick LeSabre and Pontiac Bonneville factory, affecting about a third of the 9,500 workers at its vast Buick City complex here and bringing more job uncertainty to GM's hometown.

The automaker said the assembly plant, which began building GM vehicles in 1908, will close in 1999 and the company will begin building a new engine factory in the Flint area next spring.

Most of the roughly 3,000 Buick City hourly employees will get a chance to work at other GM operations, the company said, although it didn't have an estimate of how many would be retained.

Analysts and industry observers have expected the closing for months, but union leaders were angry.

``Closing this facility is a betrayal of GM's work force, of the community and of the country, especially in light of GM's huge profits,'' said United Auto Workers president Stephen Yokich.

GM officials said the final decision was made this week, and the company wanted to end speculation that a new model would be built there beyond 1999.

Workers were told of the closing Friday afternoon. Some said they weren't surprised.

``Most of the people here have 20 to 25 years with the company,'' said Karl Freeman, a 25-year employee. ``Most will probably work at other plants.''

The new engine plant will employ some 400 workers, including several hundred of the 1,900 employees at a Flint V-8 engine factory slated to close in 1999 or 2000. Investment in the new engine plant could exceed $500 million, GM said in a news release.

The automaker said it decided it would need only two full-size car assembly plants _ in Lake Orion, Mich. and Hamtramck, Mich. GM hasn't decided yet whether to continue production of the LeSabre or Bonneville after 1999.

GM was founded in Flint and thrived there for decades, employing about 75,000 people in the area during the 1970s. The No. 1 automaker has cut more than half of those jobs since the 1970s and today employs about 35,000 people at 18 plants and offices in the Flint area.