China's Beijing Automotive Industry Corp (BAIC) has expressed an interest in buying a stake in Opel together with the rest of General Motors' European operations, for which three other companies have already entered bids this week .

The Chinese carmaker sent a letter expressing interest in Opel to Commerzbank's Dresdner Kleinwort unit, which is advising GM on the stake sale, on Thursday - a day after a bidding deadline passed, according to two people close to the deal. BAIC could not be reached for comment, and a GM spokesman at its European headquarters in Zurich declined to comment.

BAIC's offer was described as an expression of interest rather than a formal bid, and is unlikely to move forward, one of the people said. Italy's Fiat, Canada's Magna, and Brussels-listed RHJ International all entered bids for the strategic stake on Wednesday, for which GM is seeking about €650m ($900m).

BAIC is one of China's leading commercial vehicle manufacturers, and makes Hyundai passenger cars in a joint venture with the South Korean carmaker. It is the fifth largest Chinese carmaker, according to official figures.

GM's sale of a stake of Opel/Vauxhall has aroused significant interest despite its financial problems, which could see the company file for "surgical" bankruptcy protection in the US as soon as May 31.

GM's European operations are to be spun off as a new German-based company, for which the Detroit carmaker is seeking €3.3bn of German and other European government loan guarantees, and in which it will retain a significant stake. Fiat wants to merge Opel with its own autos division and recently acquired Chrysler.