Opel and Vauxhall will collapse within two years if they remain part of General Motors, workers' leaders have warned.
Union leaders say GM's revival plan - due to be presented to the U.S. government today -- will not save Germany's Opel and its UK sister brand Vauxhall.
Opel/Vauxhall are GM's second biggest selling brands after Chevrolet. In 2008, the brands sold 1.46 million new cars in Europe, including Turkey and Russia.
GM Europe's European Employers Forum, which represents 55,000 employees in Europe, is calling for Opel/Vauxhall to separate from their ailing U.S parent.
"There is no future with GM. We can only see any prospects with a divestment," Klaus Franz, EEF chairman, said.
According to union representatives, GM has drawn up a restructuring plan called Project Renaissance.
"Every scenario with the implementation of the Renaissance project in Europe will ultimately lead to a collapse of Opel/Vauxhall within one and a half to 2 years a the latest," Franz said in a statement.
If Opel/Vauxhall stay with GM, then, according to the forum:
The brands will be unable to receive loan guarantees from European governments
GM will face expensive lawsuits to lay off employees
New-car projects will be postponed
Sales will continue to plummet
Skilled staff will leave the company.
Press reports in Germany said German federal and regional governments could take a stake in Opel if GM declares bankruptcy.
The idea is considered a last resort. It was floated during talks between the federal government and German states that are home to Opel sites, the Financial Times Deutschland reported without identifying its sources.
The Westdeutsche Allgemeine Zeitung said that state governments are working on a strategy to dissolve Opel from GM.
German Chancellor Angela Merkel said at the weekend she was waiting for GM to submit its restructuring plan before deciding on any rescue plan for Opel.
Finn Ruetten contributed.