GM had given itself to the end of this month to consider bids for loss-making Saab while continuing a process to wind down the company, which has drawn interest from Dutch luxury carmaker Spyker Cars and others.
Spyker Cars Chief Executive Victor Muller said in a text message GM had extended the deadline for a final offer from Spyker Cars until January 7, in an extension of GM's original December 31 deadline for a deal. Muller added he believed there are multiple bidders for Saab.
A spokesman for GM in Europe said he had no information on the deadline being canceled and could not immediately comment.
The Swedish government has said it would allot 542 million Swedish crowns ($75 million) to measures, mainly for education and job schemes, to help deal with the thousands of jobs set to disappear if Saab shuts down.
Abandoning the 60-year-old Swedish auto brand would eliminate 3,400 jobs in Sweden and hit 1,100 Saab dealers.
In the meantime, Saab will restart some production lines again in January for its new 9-5 model and Cabrio, Saab spokesman Eric Geers said.
We have the orders and we have to deliver them as usual. We also have the orders for the 9-3 and others. The factory has to continue again, Geers said.
We are preparing the wind-down process. At the same time we are open to options, to bids that come in. Therefore the deadline has also been dropped, Geers said.
GM was still in talks with potential bidders but Geers only named Spyker Cars and declined to talk about other parties.
Loss-making Spyker has been keen to buy Saab to benefit from its technical resources and its distribution network.
Spyker, backed by Russian and Arabic investors, lodged a renewed fast-track offer to buy Saab on Dec 20.
The surprise new offer from Spyker -- which made 43 luxury cars last year against Saab's sales of 93,295 -- came just two days after talks with GM over a rescue of the loss-making Swedish manufacturer collapsed.
Spyker's Muller has said if a deal is achieved, Saab and Spyker would operate as sister companies where Spyker could benefit from Saab's technical resources and its distribution network, while Spyker would bring entrepreneurial skills to Saab.
China's Beijing Automotive Industry Holding Corp bought a number of car designs from Saab earlier this month.
(Editing by John Stonestreet and Rupert Winchester)