Germany's finance minister Wolfgang Schaeuble has pressed General Motors to provide more details of its plans for Opel and said the US-based group was responsible for workers at the European unit.

"My position is very clear: it is now up to General Motors to shed light on how it will meet its company responsibilities," he told Bild am Sonntag newspaper.

"The word from Detroit is GM doesn't need state financing for Opel. I just say: so much the better!" he added.

"With Opel, GM has a big responsibility for employees, for the regions concerned and for the whole country."

Nick Reilly, interim head of GM's European business, said on Thursday the carmaker would present a new viability plan for Opel in mid-December as it aims to reduce capacity across Europe by about 20%, Reuters noted. He said it was too soon to say whether any production sites would be closed.

Schaeuble urged GM to clarify its plans.