General Motors Chief Executive Daniel Akerson assured the CEO of Opel that the U.S. carmaker was not in talks to sell the European arm to a rival, a German newspaper reported.

Akerson spoke with Karl-Friedrich Stracke on the telephone, Handelsblatt daily reported, citing a person familiar with the matter.

German media reported last week that GM was considering putting Opel back up for sale, and both Europe's biggest carmaker Volkswagen and China's Beijing Automotive Industry Holding Co (BAIC) were named as possible buyers.

GM has so far not commented on the reports, despite calls from labor representatives and German Chancellor Angela Merkel to make a public statement on the future of Opel.

People familiar with the matter told Reuters on Thursday that GM Chief Executive Daniel Akerson was frustrated with Opel's inability to return to profitability, and was reviewing options for the European unit.

(Reporting by Maria Sheahan. Editing by Jane Merriman.)