General Motors is considering putting European arm Opel up for sale again, two German magazines reported.

Auto Bild and Spiegel Online said on Thursday that possible buyers could be Chinese carmakers or Germany's Volkswagen, which has a war chest of almost 20 billion euros ($29.3 billion).

Opel and Volkswagen both declined to comment on the reports.

In 2009, GM dropped plans to spin off Opel, backtracking on months of negotiations to sell it. It then embarked on a drastic restructuring to get the unit, which lost $1.6 billion last year, back on track.

The works council of Opel said in a statement that the reports were pure speculation and demanded a denial from parent company General Motors.

General Motors had so far kept Opel as it might otherwise lose technology and for other good reasons, Klaus Franz, head of the works council, said in a statement.

(Reporting by Jan Schwartz; Writing by Maria Sheahan and Peter Dinkloh. Editing by Jane Merriman)