Fiat plans to keep all German Opel plants open should its takeover plans for the General Motors unit succeed but would cut staff there, Fiat Chief Executive Sergio Marchionne told a newspaper.

We don't want to close any of the four Opel factories in Germany. I will need the plants in the future to build enough cars, he was quoted as saying by the Bild newspaper.

But of course staff levels have to fall. No one will be able to change that. The plants have to become more efficient.

He said he could not estimate at this stage how many of the 25,000 Opel jobs in Germany might have to go.

Germany's economy minister had said after meeting Marchionne on Monday that Opel's engine plant in Kaiserslautern might not survive a Fiat takeover.

Canadian-Austrian automotive supplier Magna is also in the hunt for GM's European business centered around Opel. GM is selling a majority stake in an attempt to get 3.3 billion euros ($4.37 billion) in state aid from European governments.

Magna wants to get into Opel with Russian help. It would surprise me if the German government would consider that a good solution, he said.

($1=.7554 euros)

(Editing by Mike Nesbit)