A traffic sign provides warning in front of the Opel plant in Bochum, Germany. (Ina Fassbender/Reuters)

Opel's works council has called for work stoppages across Europe to protest GM's decision not to sell Opel to a consortium headed by Canada's Magna International.

Klaus Franz, Opel's top employee representative, said Wednesday that brief "warning strikes" were set to begin Thursday.

Industrial union IG Metall said workers at Opel's four German plants would halt work Thursday, followed by similar moves Friday at other Opel locations in Europe.

Opel has more than 25,000 workers in Germany. GM Europe, which employs 54,000 workers in total, also markets brands including Cadillac and Chevrolet in Europe. It also produces the Vauxhall brand in Britain.

In Berlin, Economy Minister Rainer Bruederle vowed to recover the 1.5 billion euros in bridge financing Germany had provided GM Europe to keep Opel afloat until Magna and Sberbank could take a 55 per cent stake and control.

"We will get the taxpayers' money back," he told reporters, adding that GM's sudden reversal was "totally unacceptable."

British workers happier

The mood was opposite in Britain, where GM Europe builds its Vauxhall brand.

Tony Woodley, a former Vauxhall worker and joint leader of the United union, called GM's move a "fantastic decision" for the 5,500 workers at the plants in Ellesmere Port and Luton.

"There's no logic in breaking up the company. I believe it is the right decision in spite of a good deal that we'd struck with Magna," he said. "It is the best decision for Britain and our plants. I am absolutely delighted that General Motors have finally done the right thing for them and for us."