Investment company Genii Capital has withdrawn from the bidding for General Motors' unit Saab, leaving Spyker Cars as the sole remaining bidder to rescue the ailing Swedish auto brand.

Genii Capital's bid had been backed by Formula One mogul Bernie Ecclestone and had said as recently on Sunday that although Spyker Cars was well-positioned to buy Saab, Genii was ready to pounce if the Spyker bid collapsed.

But Genii said in a statement late on Monday that it was withdrawing from the race, having entered the year-long bidding process for Saab just three days before GM's original closing deadline as GM seeks to either wind-down or sell Saab.

Genii Capital believes that the timing of the next stage of the shutdown process at Saab is not compatible with its requirements for putting in place a solid business platform for the future and closing the transaction, Genii said in the statement.

General Motors Chief Executive Ed Whitacre said on Monday the company has held advanced talks with Spyker Cars over the sale of Saab, but is proceeding with plans to wind down the unit.

Obviously there have been advanced talks with Spyker cars to acquire Saab. However, we do not have a deal to announce. If and when that changes, we will let you know, Whitacre said.

Spyker with about 110 employees and Saab with 3,400 make an unlikely pairing and although the Dutch luxury carmaker's unlikely bid had flickered back into life on Monday, analysts have expressed skepticism about the chances of a deal.

(Reporting by Aaron Gray-Block; Editing by Lincoln Feast)