A key deadline to submit takeover bids for German carmaker Opel that expires on Wednesday could resolve some of the uncertainty surrounding the future of the ailing General Motors brand.

The German government expects to receive interested parties' proposals for Opel later in the day, and, at the least, Italian carmaker Fiat and Canadian-Austrian car parts supplier Magna were expected to join the bidding.

Italy's Industry Minister Claudio Scajola said he thought Fiat had a good possibility of closing a deal with Opel.

Following the deadline, it would take several weeks before a final party is selected and contracts are ready to be signed, Opel labor leader Klaus Franz told Reuters in an interview.

However, he would 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.

Any last-minute investors who have not yet voiced their interest officially must finally reveal themselves to the German government and GM.

I expect more offers than just from Fiat and Magna, Franz said.

One financial source told Reuters that Belgium-based holding company RHJ International would likely submit an offer as well.

Sources close to the German government said that German Chancellor Angela Merkel would meet with ministers including Economy Minister Karl-Theodor zu Guttenberg and Finance Minister Peer Steinbrueck following a regular cabinet meeting.

It was not clear whether they would already have the final proposals at that time.

(Reporting by Christiaan Hetzner and Angelika Gruber in Frankfurt and Gernot Heller in Berlin; Additional reporting by Philipp Halstrick; editing by Simon Jessop)