Six more hedge funds joined a lawsuit against Porsche SE over alleged securities fraud and manipulation on Thursday, with the plaintiffs doubling the damages they are seeking to $2 billion.

A spokeswoman for the plaintiffs said the six additional fund families teamed up with the existing four to seek damages from Porsche SE, which they say had deliberately deceived the market as to its intentions to build up a 75 percent stake.

Porsche SE hid that it was cornering the market in VW's freely traded (ordinary) shares by repeatedly issuing misleading statements about its activities and by spreading purchases of call options around to several counterparties to avoid detection of its increasing control, the funds said in a statement.

The scheme induced the plaintiff funds to establish short positions on VW stock, they continued.

The 35 individual funds controlled by the 10 investors listed in the lawsuit say Porsche SE aimed to trigger a massive short squeeze late in October 2008 in order to sell into the highs and rake in billions that helped rescue the automotive group from near-bankruptcy.

Porsche SE collected outrageous profits at the expense of plaintiffs, the funds added.

The investors involved include Canyon Capital, D.E. Shaw, Greenlight Capital, Ironbound Partners, Royal Capital and Tiger Global, which joined the existing group comprised of Glenhill Capital, Elliot Associates, Glenview Capital and Perry Partners, the plaintiffs' spokeswoman said.

The lawsuit is also targeted at Porsche SE's previous two top executives, CEO Wendelin Wiedeking and CFO Holger Haerter.

We received an amended lawsuit and are evaluating the accusations made therein, a Porsche spokesman said, adding that Porsche SE considers also the extended lawsuit to be unfounded and we will defend ourselves.

The Southern District of New York, the U.S. court where the case is pending, has given Porsche SE until June 15 to respond to the allegations.

COMMITTED TO PORSCHE MERGER

Volkswagen plans to subsume Porsche SE into its operations during the course of 2011. VW's two top executives, CEO Martin Winterkorn and CFO Hans Dieter Poetsch have already taken up identical positions at Porsche SE's management board after their predecessors were sacked late in July 2009.

During a conference call earlier on Thursday, Poetsch, speaking as finance chief of VW, sought to dissuade speculation that the lawsuit could derail its timetable to swallow Porsche next year and in the process gain control of the remaining 51 percent of its Porsche AG sports car unit.

As part of the agreement to form an integrated automotive group with Porsche, we undertook a thorough analysis of all the potential risks, no matter how small, Poetsch said.

We are satisfied that Volkswagen is adequately protected as regards to any potential risks occurring. I think there is no real basis to talk about any alternative scenario -- all the contractual parties are fully committed to support the merger.

VW bought a 49.9 percent interest in Porsche AG in December for 3.9 billion euros, a stake it took a small loss on in the first quarter due to accounting writedowns.

Altogether Volkswagen expects acquiring Porsche AG in its entirety will cost it 12.4 billion euros in equity and debt.

Shares in Porsche SE closed down 0.6 percent at 43.76 euros on Thursday, while VW soared 5.5 percent after it revealed strong first quarter earnings and announced progress in its aims to form a cooperation with MAN and Scania .

(Reporting by Christiaan Hetzner; Editing by Bernard Orr)