General Motors said on Wednesday it expected at least three bidders for a stake in Opel to hand over plans to the German government ahead of a 1600GMT deadline.

A GME spokesman would not name names but Fiat and Magna have confirmed interest while US investment fund Ripplewood is also reportedly throwing its hat into the ring, news agency AFP said.

The final decision on who buys GM Europe, which includes Opel in Germany and Vauxhall in Britain, lies with GM itself and with the US government, but the German government will sweeten any deal with millions of euros in loan guarantees.

AFP said Fiat is the most prominent bidder for Opel and wants to combine GM's European operations with Chrysler to create the world's second largest carmaker behind Toyota.

Magna has teamed up with Russian state-owned lender Sberbank and automaker GAZ owned by tycoon Oleg Deripaska.

Bidders making a formal offer will be expected to come up with around EUR650m, the FT reported on Wednesday, saying that GM would give preference to cash bids.

A Fiat spokesman told AFP on Tuesday the firm intended to offer assets instead of cash, in a similar model to its recent deal securing a stake in Chrysler.

Italian daily La Repubblica cited on Wednesday the letter of intent that Fiat is handing over in Berlin as saying the firm will put on the table know-how and its vast sales network.

"We are in crisis but we still have a value," Klaus Franz, the head of Opel's powerful works council told the FT. "Such remarks are bursting with arrogance and disrespect for the employees at Opel."

AFP noted that the German government had drawn up emergency plans involving a special trustee and bridge financing to keep Opel going in the event of a GM bankruptcy.

Separately, German labour minister Olaf Scholz was quoted by Reuters saying preliminary decisions on Opel's future must be made by the beginning of next week.

"We don't have much time. Decisions must be made this week, or at the latest by the start of next week", Scholz told a news conference in Berlin, after a government meeting on bridge financing for Opel in the event that GM files for bankruptcy.

Scholz said further top-level government meetings on Opel were scheduled.