BERLIN (Reuters) - The German government is not involved in talks on the sale of insolvent German airline Air Berlin's (>> Air Berlin Plc) assets, an Economy Ministry spokesman said on Friday, adding there was no deadline for any deal to be sealed.

The comments were made after Transport Minister Alexander Dobrindt called for market leader Lufthansa (>> Deutsche Lufthansa) to buy a major part of the assets of Air Berlin, Germany's second-largest airline, saying Germany needed a "national champion" in international aviation.

"The companies are negotiating now. The government is not sitting at the table there and is also not steering this," Economy Ministry spokesman Korbinian Wagner said during a regular government news conference in Berlin.

The German government does not have a preferred outcome for the Air Berlin negotiations and it is now up to the companies involved to find a solution, the spokesman added.

The Economy Ministry spokesman said no time frame had been set for the government's bridging loan of 150 million euros ($176 million) to Air Berlin. He said the aim was for the sum to be sufficient to find a sustainable and sensible solution.

The government granted the loan to allow Air Berlin to keep its planes in the air for three months and secure the jobs of 7,200 workers in Germany while negotiations continued.

Economy Minister Brigitte Zypries had made clear that more than one airline needed to come forward for Air Berlin for competition reasons, the Economy Ministry spokesman said.

(Reporting by Michael Nienaber; Editing by Michelle Martin and Edmund Blair)