FRANKFURT, Germany - German luxury sports car maker Porsche is still in exclusive talks with Qatar on a possible Qatari stake in the company but is unable to give a date for a deal, a spokesman told AFP on Monday.

"We are talking exclusively with Qatar," the spokesman said following press reports that others were interested in buying Volkswagen stock options owned by Porsche.

State-owned funds in China and Russia were among those mentioned, according to the business daily Handelsblatt, which quoted a Porsche spokesman.

But "we deny this declaration," the Porsche spokesman told AFP. "This is speculation on which we will not comment."

Heavily-indebted Porsche said last week that it had received an offer from the Qatar Investment Authority and expressed confidence it would reach agreement on selling a direct stake in Porsche and VW stock options.

A deal would allow Porsche to pay off some of the nine billion euros (S$18.2 billion dollars) in debt it accumulated trying to increase its holding in VW, the biggest European car maker.

Porsche currently owns around 51 percent of VW.

On Monday however, Porsche could not say when a deal might be signed.

Discussions with Qatar have been troubled by a dispute between Porsche's two main shareholders, the Porsche and Piech families.

They met last week for talks, the spokesman said, without providing details.