Opel's supervisory board was holding an extraordinary meeting on Wednesday morning to decide on the carmaker's legal separation from its parent General Motors, a person familiar with the matter has said. It has also emerged that a Chinese automaker has submitted a last-minute bid.

The supervisory board was set to approve a transfer of Opel's non-German European plants to German unit Adam Opel GmbH, the person told Reuters.

Financially, Opel is already separate from the parent company, another source has told Reuters.

The German government is due to decide on Wednesday evening which bidder or bidders it prefers as a partner for Opel. It wants to act quickly in case GM files in the United States for Chapter 11 protection from creditors, the news agency said.

The government has been considering offers from Fiat, Magna International and Belgium-listed industrial holding RHJ International but Chinese automaker Beijing Automotive Industry Holding (BAIC) has surprisingly emerged as a last-minute contender. A spokesman for Berlin's economy ministry told Reuters the company had submitted a bid late on Tuesday.

BAIC builds Hyundai cars and is China's fifth largest car producer.

GM will make the final decision on who buys Opel but the German government's opinion is crucial as it is will guarantee loan for billions of euros as part of any deal.