Movie bosses financing the forthcoming prequel "Star Wars: Episode III - Revenge Of The Sith", are threatening legal action against Internet sites that leak pictures and plot details.

The Internet Media Database reported that many websites are currently displaying photographs of a pregnant Padme Amidala, played by Natalie Portman, and a new android villain named General Grievous.

Other shots screened online include an aggressive light-sabre duel between Anakin Skywalker and his former mentor Obi-wan Kenobi - which leaves Skywalker horribly scarred and propels him to don the black suit of Darth Vader.

Producers of the film had issued a warning to the Internet sites last year and have now renewed their threat of legal action.

"Star Wars...", which is due to hit cinemas in the US May 19, is reported to be the opening film at the Cannes festival.