Six Hollywood studios have filed a legal suit against RealNetworks for releasing an application which allows users to copy commercial DVDs.

Paramount Pictures, 20th Century Fox, Universal Studios, Warner Brothers, Columbia Pictures, Walt Disney and Sony are suing the company and seeking an injunction to stop any further sales of the RealDVD software.

"RealNetworks' RealDVD should be called StealDVD," said Greg Goeckner, general counsel for the Motion Picture Association of America.

"RealNetworks knows that its product violates the law and undermines the hard-won trust that has been growing between America's movie makers and the technology community.

"We will vigorously defend our right to stop companies from bringing products to market that mislead consumers and clearly violate the law."

RealNetworks argues that its software still encrypts copies of DVDs and thus stops them from being shared on peer-to-peer networks.

"We are disappointed that the movie industry is following in the footsteps of the music industry and trying to shut down advances in technology, rather than embracing changes that provide consumers with more value and flexibility for their purchases," RealNetworks said in a statement.

However, the studios claim that the software is being used in "rent, rip and return" scams, where DVDs are rented from firms like Blockbuster or Netflix, copied and then returned to the store.

The studios are suing under the Digital Millennium Copyright Act which prohibits the sale of software that circumvents copy protection systems.