Dutch luxury carmaker Spyker submitted an improved bid for Sweden's Saab to General Motors Co on Thursday, just ahead of a key deadline that could prompt closure of the brand.

We have continued a constructive dialogue with GM over the acquisition of Saab. We believe the Saab brand has lots of potential and would be keen to close a deal as quickly as possible, Spyker Chief Executive Victor Muller said in a statement Thursday.

GM , which three weeks ago said it would shut down the 60-year-old automaker, did not indicate how it would treat Spyker's bid or any other bids for Saab.

At least two other bids for Saab were submitted to GM on Thursday, according to a report in Sweden.

GM continues to receive and evaluate proposals for Saab, GM said in a statement. We consider any discussions to be confidential, and we won't discuss any details until a decision is reached.

More than 3,000 workers in Sweden will lose their jobs if Saab cannot be saved.

On Wednesday, GM Chief Executive Ed Whitacre said he was not confident of reaching a deal to save Saab, citing difficulty by potential buyers in arranging financing for a purchase of the money-losing brand.

GM has said it is moving ahead with plans to wind down Saab operations first announced in mid-December but could stop that process if it finds a buyer for the brand under the right conditions.

Earlier on Thursday, Muller had told Reuters he was confident that we will put in an acceptable bid.

A person with knowledge of the negotiations said Swedish parties were in talks with GM ahead of a meeting of Saab's board set for Friday.

Swedish labor union newsletter Dagens Arbete said on Thursday that Luxembourg-based investment firm Genii Capital had made a bid for Saab and has met Swedish officials to inform them of the plans.

Swedish daily Dagens Industri reported that two Swedish groups were submitting bids for Saab, and one was backed by Genii Capital. The report said the group would use the business plan drawn up by small Swedish luxury carmaker Koenigsegg, which pulled out of talks to buy Saab in November.

The other Swedish group, according to Dagens Industri, includes Hakan Samuelsson, a former Man AG chief executive. that bid calls for a smaller and split Saab and does not call for loans from the European Investment Bank said.

Koenigsegg was said not to be involved in the new bids.

The notoriety of the Saab name is what would be valuable to any buyer, an analyst said.

The actual equity in the brand is probably well beyond the value of market share of the company, said Michael Tyndall, an auto industry analyst at Nomura International. The technology belongs predominantly to GM.

Tyndall saw little chance of a reversal on GM's decision to start winding down Saab. The idea of there being an 11th hour white knight seems far-fetched to me, he said.

Abu Dhabi's Mubadala Development Company owns about 23 percent of Spyker shares, according to a January 2008 filing with Dutch market regulator AFM.

Convers Group, a Russian bank controlled by the Antonov family. Convers holds a 29 percent stake in Spyker and Alexander Antonov's 34-year-old son, Vladimir, is chairman of the carmaker's board.

Spyker's bid to buy Saab has faced skeptics from the start given that the Dutch company has never made a profit. Saab has also been consistently unprofitable in the 20 years it has been controlled by GM.

General motors