General Motors Co is considering a plan to raise funding to keep Opel as an alternative to selling the unit to Magna International with financing from the German government, sources with knowledge of the deliberations said on Monday.

GM's board met Friday and asked management led by Chief Executive Fritz Henderson for more information on the Magna bid, declining to endorse a deal that has been under negotiation for months.

While GM remains focused now on trying to clear remaining issues with the Magna deal, executives are also giving consideration to other options, including raising more than $4 billion in a bid to keep Opel, sources said.

GM had no immediate comment.

Because GM is barred from using funding from the U.S. government from its reorganization in bankruptcy to support its international operations, one of the options could include raising money by selling or mortgaging the automaker's assets in China, one of the sources said.

(Editing by Steve Orlofsky)