RHJ International SA (RHJI.BT) Monday said it is in advanced talks with General Motors Corp. (GMGMQ) about buying a stake in Adam Opel GmbH, confirming it is still in the running for the GM subsidiary.

Investment group RHJ, which until recently appeared to have dropped its pursuit of Opel, said is has been in talks with GM "over a number of weeks." Further details were not provided.

The confirmation means Magna International Inc. (MGA), which signed a memorandum of understanding with GM in late May for a stake in Opel, faces another rival for the company. Earlier this month Beijing Automotive Industry Holding Co. Ltd. submitted a detailed proposal to GM offering EUR660 million for a 51% stake, according to a document reviewed by Dow Jones Newswires.

GM has said it is open to other potential bidders for Opel, and its agreement with Magna is non-binding and not exclusive.

Magna's supervisory board is set to discuss the company's Opel offer Tuesday, but it is unlikely to close a deal this week. German Economics Minister Karl-Theodor zu Guttenberg said Thursday that finalizing a takeover this week was "a very ambitious goal," and there are still a number of details to iron out.

The head of Opel said in a letter to staff last week that while having several interested investors was positive, he was keen to close the sale. "We need a deal fast," Hans Demant said in the letter.

Opel's union supports Magna's offer, and the German government, based on Magna's proposal, provided bridge financing to keep Opel operating while GM went through insolvency. Magna's bid for Opel is backed by Russia's Sberbank Rossia (SBER.RS) and automaker OAO GAZ Group (GAZA.RS).

-By Adam Cohen and Sarah Sloat, Dow Jones Newswires; +322 741 1486; adam.cohen@dowjones.com, sarah.sloat@dowjones.com