Sith is attacked by the clones

The movie was only released in cinemas yesterday. But not even George Lucas has been able to use the force to prevent his final Star Wars film being leaked on the Web.

Episode III - Revenge of the Sith has appeared on a file-sharing network in the form of a 'work print copy'. A tracker site showed thousands of people trying to download it.

The film is expected to take millions of pounds at the box office but a US consulting firm has calculated the film's Net release could cost more than £300million in lost productivity as DVD pirates flood the market with illegal copies.

Sleeves for pirate copies of the film and discs with director George Lucas' introduction to the movie have already been seized in London. The film completes the epic story of Anakin Skywalker's seduction by the Dark Side of the Force.