But reports said GM's new appointed board of directors wants to know from the German government about financial backing for a rival bid by RHJ International.

Magna and Sberbank have offered $775 million to acquire a 55 percent stake in Opel and its UK unit Vauxhall. GM will retain 35 percent, and Opel employees acquire 10 percent under the deal.

But GM chief negotiator John Smith reportedly has reservations about Magna's offer because it will give its Russian partner access to GM intellectual property and control over some of its Chevrolet operations in Russia.

Magna's consortium with the Russian bank has the backing of the US, Canadian and German governments because of the emerging middle class in Russia which could fuel Opel's long-term recovery.

Being the majority stake holders in GM currently, the US and Canadian governments also have a big say in the bidding process.

The German government is also a big player as it negotiated and underwrote a deal to transfer Opel assets to a new company before the GM bankruptcy.