Vauxhall and Opel will shed around 9000 jobs across Europe, the company has confirmed.
The plans were outlined to Vauxhall and Opel workers' Employee's Forum by GM's European boss Nick Reilly this morning, and announced this afternoon.
Reilly said 50-60 per cent of the job losses would be in Germany, with the rest spread around the company's plants in Britain, Belgium, Spain and Poland. No further details were given on where the job losses would be concentrated, and no specific information on Vauxhall was released.
The specific numbers of job losses or plant closures could not be confirmed, as a period of consultation will now begin as those affected discuss their options.
However, Reilly identified only the Antwerp plant in Belgium as having an "uncertain" future. GM has agreed to set up a working group to assess prospects for the Belgian plant, Reilly said.
"We hope to finish the consultation some time in December - in the next two to three weeks," said Reilly. "We have had specific requests to provide more information to those affected, and that is what we must do next.
"Our objective is to create a viable and sustainable plan for Vauxhall-Opel. I believe that is doable and look forward to working with representatives to put this plan into effect."
Reilly also said GM's European headquarters would be based at Germany's Ruesselsheim plant, a move from Zurich, Switzerland.
He also confirmed that GM would now approach governments in countries where it has plants to discuss funding support. He added that GM itself was prepared to provide investment, despite having its own financial troubles and relying on US government support, as it would "make GM stronger globally".
GM is believed to need around 3.3 billion euros (£3bn) of funding to complete its restructuring plans for Vauxhall-Opel.