German authorities currently calculate Opel's cash needs at €3.3 billion ($4.2 billion), the newsweekly Der Spiegel said, without citing its sources. Until now, the auto manufacturer was believed to require €1.8 billion in loan guarantees, the magazine said in an article to appear on Monday.
Parts of the report were released in advance. Opel immediately issued a statement that neither confirmed nor denied the mooted figure. "We are not giving a figure," a spokesman for GM Europe added when contacted by news agency AFP.
The Opel statement said: "It is the responsibility of Opel management to establish a realistic portrait and to take changes in the European market into account within the framework of requests for public guarantees."
A spokesman for the regional finance ministry in the German state of North Rhine-Westphalia told AFP that the body that examines requests for public aid would make a decision in early April. Opel was expected to present a viable business plan for the future "within two weeks," the spokesman added.
Like its rivals, Opel has been slammed by slumping auto markets, especially in Europe. The German group must also deal with financial problems facing its parent company, which has only avoided bankruptcy with help from the US government. GM directors opened the door this week to an Opel spin-off within the framework of a broad restructuring of GM's European activities.