Munich - German officials are increasingly reluctant to arrange a separate rescue deal for the German subsidiary of General Motors (GM) after concluding that it has no assets, a news magazine reported Saturday.

At the same time, both German labour leaders and the chief executive of GM Europe insisted serious talks were still being pursued to bring in an outside investor at the Opel volume carmaking unit.

The magazine Focus quoted an unnamed German minister saying Opel's patents, plant and real estate had already been mortgaged to the US government and US banks as security for loans, and could thus not be acquired by a new investor.

"Opel is just an empty shell," the minister was quoted as saying. "GM no longer has any authority over the assets."

He added that separating Opel from the rest of GM would be far more complicated and costly than anyone had realized so far.

A new investor would have to negotiate the takeover with the US government and the banks.

Focus released the report two days before its print edition appears Monday.

Another news magazine, Der Spiegel, quoted GM Europe chief Carl-Peter Forster saying potential private-equity and sovereign-capital investors remained interested in buying into the European unit.

He told Spiegel that even if the GM parent company declared insolvency, production and sale of Opel and Vauxhall cars in Europe would continue as normal.

Klaus Franz, who heads the Opel labour representation council, told the German Press Agency dpa there were "a whole lot of interested investors" from around the globe, but declined to name any.

But he rejected as "unlikely" a report in the German newspaper Westdeutsche Allgemeine Zeitung that Abu Dhabi was putting out political feelers for a stake. Abu Dhabi's capital fund bought a major stake in German car company Daimler last month.

In a related development, a former German chancellor, Gerhard Schroeder, said there might be a "crisis of confidence in democracy" if efforts to put Opel back on its feet were to fail. He accused supporters of Chancellor Angela Merkel of "doing nothing." (dpa)