Adam Opel GmbH said efforts to try to rescue its Bochum car plant in Germany had been to no avail and it still intended to stop vehicle production there in 2016.
"The main reasons are the dramatic declines in the European car market and the enormous overcapacity in the entire European auto industry," the unit of U.S. carmaker General Motors told Bochum's roughly 3,000 workers on Monday.
While the crisis in Europe's auto industry has seen Ford Motor Co. and PSA Peugeot Citroën announce plans this year to each close a car plant, Opel would be the first carmaker to shutter a plant in Germany in decades.
Opel said interim chief executive Thomas Sedran told a closed meeting of Bochum's work force that management saw no alternative to the move, which will likely add to the hardships of the economically depressed Ruhr region.
The planned measures at Bochum, coinciding with the end of the lifecycle of the Zafira Tourer MPV model, were announced in mid-June when management and unions agreed to talks over Opel's German operations, which employ 20,800.
The head of IG Metall's regional chapter in North Rhine-Westphalia (NRW) said he would continue to fight for manufacturing jobs in Bochum after 2016.
"Our goal is clear - no one should see the unemployment agency from the inside," IG Metall NRW boss Knut Giesler said.
"An executive who tells workers that manufacturing will come to an end, only to then avoid a discussion by leaving through the emergency exit leaves a devastating impression behind him."
Opel denied Mr. Sedran had dodged a debate with staff.
Monday's announcement left in doubt labour's hopes of reaching a deal this year over the restructuring of Opel's German operations. "We are further away from negotiating an agreement than before. A deal is scarcely possible before Christmas, probably," said a spokesman for IG Metall NRW.
When asked by Reuters if a deal prior to the holidays was achievable, Opel's top labour leader Wolfgang Schaefer-Klug said: "We will try".
A working group called "Bochum Prospects 2022" that GM has helped create should manage to save some jobs at the site, although they may be with other companies.
"We have the clear intention to secure a significant number of Opel jobs (in Bochum), in the warehouse and possibly in component manufacturing," GM vice chairman Steve Girsky in a statement.
About 430 people who work in Bochum's warehousing operations are employed by a joint venture with GM partner CAT Logistics, now called Neovia Logistics Services and minority-owned by Caterpillar.
An Opel spokesman at its headquarters in Ruesselsheim said the number could grow to 600 or more after negotiations.
A drop in demand for the Zafira Tourer is already hurting Bochum. There are talks to stop the assembly line for 10 days in January and cut production by about half. Next year could also see the loss of the night shift, the local works council said.
An IG Metall committee will now meet in Frankfurt on Wednesday to discuss how to proceed following the announcement that Opel management saw no alternative to its plan to end vehicle production in Bochum in 2016.