Hayden Christensen in a scene from Star Wars: Episode III ? Revenge of the Sith. (Reuters)

London, May 19 (Reuters): The final chapter of the Star Wars saga has gone over to the Internet's dark side.

Star Wars: Episode III ? Revenge of the Sith has been leaked onto a major file-sharing network just hours after opening in theatres, at a time when Hollywood is increasingly concerned about online piracy.

At least two copies of the film, first shown in theatres early yesterday, have been posted to the BitTorrent file-sharing network ? a new and increasingly popular technology that allows users to download large video files much more quickly than in the past.

The Motion Picture Association of America (MPAA) has been aggressive in going after websites that provide “tracker” links that enable BitTorrent downloads of copyrighted material, filing six lawsuits this week against sites with links to TV shows.

According to website waxy.org (www.waxy.org), one print of Revenge of the Sith was leaked on Wednesday before the film was even released in theatres. The movie was time-stamped, suggesting it may have come from within the industry rather than from someone who videotaped an advance screening.

One popular tracker website showed more than 16,000 people currently downloading the film via BitTorrent.

Hollywood is trying to avoid the fate of the music industry, which claims it has lost hundreds of millions of dollars worth of sales to illicit file-sharing networks.

Movie files are about 50 times larger than music files, which makes them much more cumbersome to download, but new technologies like BitTorrent and increased high-speed Internet penetration are closing the gap. There was no official comment from privately held Lucasfilm Ltd.