Rhineland-Palatinate premier Kurt Beck, from the centre-left Social Democrats, said the affected states had an agreement with the federal government to co-operate in keeping the firm, which employs 25,000 German workers, in business.

“The federal government and the four affected states have a clear agreement – to which I’m sticking,” Beck said.

It was “not acceptable for the federal government to back out of an agreement, which we only made 10 days ago,” he added.

North Rhine-Westphalia’s premier Jürgen Rüttgers of the conservative Christian Democrats was less overt in his criticism, but pointedly remarked that the federal government should not be making definitive statements on its own.

He said Opel’s parent company, US automaker General Motors, needed to state clearly how it was going to rescue Opel.

Opel and GM are currently drafting a rescue plan which they are supposed to present to the German government.

As soon as a plan was made, the federal and state governments would “respond as one – as they have before,” Rüttgers said.

However, Hessian premier Roland Koch, also from the Christian Democrats, stepped back from the fray, saying there was nothing to debate until Opel presented its rescue plan.

“There is no need for a discussion,” he said. “The ball is in Opel’s court.”

Brüderle, from the pro-business Free Democrats told Bild am Sonntag that GM could expect at the most financial help only from the four affected states, and that there would be none from the federal government.

Those states are North Rhine-Westphalia, Hesse, Thuringia and Rhineland-Palatinate.

Brüderle’s tough stance has also put him at odds with federal cabinet colleagues, including Finance Minister Wolfgang Schäuble, who recently told business magazine Wirtschaftswoche that if Opel needed help to save German jobs, the federal government would need to step in.

Berlin pledged to kick in €4.5 billion when it expected GM to sell Opel to Canadian auto parts group Magna. GM then changed its mind and decided to keep Opel.

But Schäuble said the German government couldn’t stand by a pledge for one owner but not another if German jobs were at stake.