A preferred bidder for General Motors Corp.'s (GM) German unit Adam Opel GmbH is unlikely to be selected Wednesday, German government spokesman Thomas Steg said.

He said talks on the carmaker's future will probably continue with at least two investors.

"It is rather unlikely that the result of tonight will be that future negotiations will only be conducted with one investor," Steg told reporters.

But he said it is open whether they will agree "on a succession, a ranking a preference list," and the meeting won't end without any result.

Steg also said no clear plan has been provided by China's Beijing Automotive Industry Corp., which isn't participating in the talks at the moment. However, he doesn't rule out talks with the Chinese bidder later.

Talks with the U.S. Treasury and GM over Germany's plan to provide bridge financing have made progress, in particular concerning the planned trusteeship model, in which the federal and state governments would give guarantees for Opel.

"Details will be addressed. We plan to look into it intensively," Steg said, adding it remains open whether the U.S. Treasury, which will attend Wednesday's meeting in the chancellery, can give certain declarations and commitments for the trusteeship model.

Bidders for Opel can outline more details and improvements to their offer for Opel in a meeting with government officials from 1500 GMT and top government officials will join the talks from 1830 GMT.

The final meeting late Wednesday will include Chancellor Angela Merkel, key cabinet ministers, governors of the German states with Opel plants, representatives from GM and the U.S. Treasury and the bidders.

Germany will decide at this meeting whether it regards at least one of the three bids as solid. This is a precondition for offering a trusteeship model for Opel which would allow giving bridge financing to the company for the next months to allow negotiations with investors to continue.

The bridge, or interim, financing of around EUR1.5 billion would be from state-owned bank KfW and Landesbanken of the states with Opel plants. Austrian-Canadian Magna International Inc. (MGA) and Italian automaker Fiat SpA (F.MI) are believed to be leading a field of bidders for the company.

Financial investor RHJ International SA (RHJI.BT) has launched a rival offer and Tuesday, Chinese automaker Beijing Automotive Industry Corp. (BAIC) emerged as a possible fourth bidder.

   -By Beate Preuschoff and Andrea Thomas, Dow Jones Newswires, andrea.thomas@dowjones.com; +49 30-2888-4126