General Motors Corp. (GMGMQ) said it will end its 25-year manufacturing joint venture with Toyota Motor Corp. (TM) in Fremont, Calif., dealing the Japanese auto maker another blow as it struggles to right its U.S. operations.

Toyota, which last year posted its first annual loss in nearly 70 years, said GM's withdrawal from the venture - known as New United Manufacturing Inc., or NUMMI - will aggravate already-difficult business conditions.

"While we respect this decision by GM, the economic and business environment surrounding Toyota is also extremely severe, and so this decision by GM makes the situation even more difficult for Toyota," the company said in a statement Monday.

The plant currently produces the Pontiac Vibe, which GM will stop making within 60 days, as well as the Toyota Corolla car and Tacoma compact pickup truck.

Toyota plans to continue building the Corolla and Tacoma at the NUMMI factory, at least for now, Toyota spokesman Mike Goss said.

"We don't know what's in store for the future," he said.

When NUMMI kicked off in 1984, a stodgy GM saw it as a chance to absorb Toyota's revolutionary system of lean manufacturing and streamlined business practices. At the time, Toyota was mulling whether to begin producing vehicles in North America. It viewed the joint venture as an opportunity to test its production system on a U.S. workforce.

The future of the factory grew cloudy last week when GM announced plans to discontinue the Pontiac Vibe by the end of August. The auto maker is selling or ending four of its eight brands and eliminating many models as it scrambles to slim down and restructure in bankruptcy court.

Toyota vehicles account for nearly three-quarters of the plant's overall output.

"We have enjoyed a very positive and beneficial partnership with Toyota for the past 25 years, and we remain open to future opportunities of mutual interest," said GM North America President Troy Clarke.

GM's ownership interest in the venture will become part of "old GM" to be sold off as part of the bankruptcy proceedings.

-By Sharon Terlep, Dow Jones Newswires; 248-204-5532; sharon.terlep@dowjones.com

(Kevin Kingsbury contributed to this report.)