Cash-strapped General Motors
Opel's woes are part of parent company GM's struggle to survive as it turns to the U.S. government for emergency aid and faces a June 1 deadline to restructure its bond debt and reach a deal with its major union.
A spokesman for GM Europe said interest was concrete enough to expect at least three bids for a stake in Opel on Wednesday.
Fiat SpA Chief Executive Sergio Marchionne recently agreed to take a stake in U.S. maker Chrysler LLC and has outlined plans to form the world's second-largest autos group behind Japan's Toyota Motor Corp <7203.T> by bringing together Fiat, Chrysler and GM assets including Opel and its UK affiliate, Vauxhall.
Another bidder for a stake in Opel is Canadian-Austrian parts supplier and auto assembler Magna
Belgium-based holding company RHJ International
Earlier this month Russian bank Sberbank said it was also considering a role an Opel deal, which German media said could involve a bid teamed with Magna.
Opel sought 3.3 billion euros ($4.50 billion) in state loans and guarantees from European countries where it has factories as part of a restructuring plan.
Fiat has told the German government it would need up to 7 billion euros from relevant governments if it enters into a deal to take a stake in Opel.
Fiat's Chrysler deal also involves the U.S. government aid.
Magna has proposed opening up under-used Opel plants to other automakers and allowing them to use Opel platforms to bring niche models to market quickly.
Italy's Industry Minister Claudio Scajola said he thought Fiat had a good chance of closing a deal.
One group less enthused about Fiat's proposal is Opel's unions, which fear that overlapping product ranges could spell plant closures in Germany, Austria, Britain or Belgium.
German states where Opel has plants are willing to offer up to 750 million euros in bridge financing for Opel, Juergen Reinholz, economy minister of German state Thuringia, said on Wednesday.
Opel labor leader Klaus Franz told Reuters in an interview that a final deal for Opel could take several weeks but he did not exclude the possibility that a letter of intent could be presented this week.
It will be a crucial issue whether an investor submits a memorandum of understanding which then would form the basis for further negotiations, he said.
If an investor is really interested in us, then that could certainly be the case. I can definitely imagine that.
I expect more offers than just from Fiat and Magna, Franz said.
German Chancellor Angela Merkel will meet with ministers including Economy Minister Karl-Theodor zu Guttenberg and Finance Minister Peer Steinbrueck following a regular cabinet meeting, sources close to the German government told Reuters.
Opel's future is a hot political topic ahead of German elections in September, and Berlin wants to find a quick solution. GM will decide which investor gets Opel, but it has said the German government will play a big role.
On Tuesday, the government reached agreement with major banks on a way to provide bridge financing for Opel if needed, the European Investment Bank said.
The German government wants Opel assets ring-fenced from GM creditors and overseen by a trustee if GM is forced to file for bankruptcy.
(Reporting by Christiaan Hetzner and Angelika Gruber in Frankfurt and Gernot Heller in Berlin; Additional reporting by Philipp Halstrick; Editing by Jason Neely and Hans Peters)