Investors including U.S. hedge fund Elliott Associates have escalated a legal battle against members of Porsche's supervisory board by seeking 1.8 billion euros ($2.43 billion) in damages from Wolfgang Porsche and his cousin Ferdinand Piech.

The most recent lawsuit forms part of a legal campaign being waged by in various courts across the world, seeking to recoup money which was lost by betting on a decline of Volkswagen's share price in 2008.

On Sunday, Porsche dismissed the most recent lawsuit, which was lodged at a Frankfurt regional court, as "unfounded". Ferdinand Piech and Wolfgang Porsche were not immediately available for comment.

A spokesman for Elliott Associates declined to comment.

"Porsche SE and its supervisory board members will defend themselves with all available legal means," Porsche said on Sunday, adding that the lawsuit in Frankfurt was no different to a separate lawsuit already pending in Hanover.

The funds have accused Porsche of engineering a "massive short squeeze" in October 2008 by quietly buying nearly all freely traded ordinary VW shares in a bid to take over the company, despite publicly stating it had no plans to do so.