Le Monde newspaper had reported on Tuesday that France's PSA was looking to sell part of Opel's R&D operations to help to restore profitability to the loss-making unit.

"A sale of Opel's development would rob Opel of its future. The technological heart of the Opel brand lies in engineering," Opel's works council said in a statement, vowing to fight any attempt to sell all or part of the R&D arm.

It called a staff meeting for Thursday and asked Opel Chief Executive Michael Lohscheller to address workers there.

PSA and Opel had already sounded out automobile engineering firms over the last few months so that they can submit offers for four sections of the business that are valued at about 500 million euros (440.72 million pounds) in total, Le Monde said.

Opel said on Wednesday that no decision had been made on the future of the R&D arm but that restructuring as part of a savings plan could include strategic partnerships.

"We know that the workload from GM will decrease drastically over the coming years. Therefore, we are looking into different options on how we can achieve a sustainable and successful set-up in the Engineering Center," CEO Lohscheller said in a statement.

PSA last year bought loss-making Opel and British sister brand Vauxhall from General Motors in a $2.6 billion deal. It aims to restore profitability at Opel by 2020 after two decades of losses at the unit.

A spokesman for Germany's Economy Ministry said that the government's aim was to ensure that Opel retains R&D activities in Germany after the brand's sale to PSA.

RESTRUCTURING DEAL

PSA agreed in late May on an investment plan and job guarantees for German factories in return for wage concessions, ending a standoff with powerful labour union IG Metall.

But labour representatives and Opel management are still working out some details of the plan, with an eye to signing a collective agreement this week, which could now be complicated by the reported plan to sell part of the R&D business.

The Le Monde report said four firms, Altran, Akka and Segula, all French, and German company Bertrandt had been approached.

Citing an internal document from mid-May, the newspaper said the sale would cover Vehicle Engineering, Propulsion Engineering, Tool & Die Operations and the test centre.

The sections employ about 3,980 people, including at Opel's historic headquarters in Russelsheim, and according to the document the sale could happen by the end of the year.

(Reporting by Matthias Inverardi and Thomas Escritt; Writing by Maria Sheahan; Editing by Douglas Busvine/Keith Weir)