China's Beijing Automotive Industry Holding Co. plans to present a detailed bid for General Motors Corp.'s (GMGMQ) core European Adam Opel GmbH operations within the next few days, hoping to step in should takeover talks with Magna International (MGA) turn sour, a person familiar with the matter said Wednesday.

In May, GM signed a memorandum of understanding to sell a sale of a majority stake in Opel and its U.K. sister brand Vauxhall to Canadian auto supplier Magna, which has launched an offer backed by Russia's Sberbank (SBER.RS) and automaker GAZ (GAZA.RS). The agreement isn't legally binding, but Opel's powerful labor unions have already voiced their support.

BAIC held discussions with GM last week about the possibility of bidding for Adam Opel, the Wall Street Journal reported June 25, citing a person familiar with the situation. The Chinese company, which expressed its interest in the unit in a letter of intent to Germany's economy ministry in May, has since offered more detail.

Magna still appears to be the front runner, though talks continue with BAIC and RHJ International (RHJI.BT), another person familiar with the matter said.

The tentative agreement with Magna is backed by EUR1.5 billion in bridge financing provided by the German government to keep Opel afloat as parent GM filed for bankruptcy protection in the U.S.

-By Christoph Rauwald, Dow Jones Newswires; +49 69 2972 5512; christoph.rauwald@dowjones.com;

  (Norihiko Shirouzu of The Wall Street Journal contributed to this article.)