The Gulf emirate of Qatar has offered €7 billion for a stake in Porsche, which would allow the German luxury sports car maker to clear a large part of its debts, a report said yesterday.

According to the weekly Der Spiegel, the Qatar Investment Authority would take 25 per cent of Porsche Automobil Holding and options on Volkswagen shares currently held by Porsche.

In addition Volkswagen, which has proposed buying 49 per cent of Porsche's core sportscar operations, has upped its bid to more than €4 billion, Der Spiegel said, without quoting sources.

Porsche has scheduled an extraordinary meeting of its supervisory board on July 23 to discuss offers by Qatar and Volkswagen, sources have said.

Porsche has run up some €9 billion in debt it accumulated in a failed attempt to increase its holding in VW, the biggest European car maker.

It currently owns about 51 per cent of VW, which has made its counter offer in a boardroom drama between the carmakers' dominant influences, the Porsche and Piech families.

A takeover of Porsche by VW would reinforce the power of Ferdinand Piech, a major shareholder in Porsche and head of the VW supervisory board.

A deal with Qatar would boost Wolfgang Porsche and give his company a chance to renew its takeover bid for the much bigger VW, and preserve the chances of Porsche boss Wendelin Wiedeking keeping his job.