BERLIN (AFP)--Troubled German carmaker Opel is threatening to close three of its plants in Europe and sack 11,000 people, one fifth of its workforce, as it seeks billions of euros in state aid, reports said Saturday.

According to the weekly Der Spiegel to be published Monday a plan submitted to government officials Friday calls for the closure of factories at Bochum in western Germany, Eisenach in the east and Antwerp in northern Belgium.

The aim is to save some EUR949 million in staff costs, Der Spiegel said. An alternative proposal would be to cut only 3,500 jobs but lower wages across the board, it added.

Another weekly Focus said Opel, a subsidiary of ailing U.S. auto giant General Motors Corp. (GM), was demanding EUR4 billion in state aid, not the EUR3.3 billion reported earlier, though some could be in the form of guarantees or credits.

A company spokesman said Friday that talks on a rescue package could last weeks, after directors from Opel and its US parent General Motors met German officials at Chancellor Angela Merkel's office in Berlin.

German officials are concerned that Opel's strong dependence on GM would lead to state aid effectively being transferred to the U.S.

Focus noted that Opel had never paid a single cent in taxes to the German state, as any profits it made were transferred to Detroit.

In her weekly video address, meanwhile, Merkel said that Opel's proposals needed "improvement."