Pirate copies of blockbuster hit The Matrix Reloaded were available to download online, less than two weeks after the film went on release around the world, BBC News Online has learned.
The third film, The Matrix Revolutions, will open in November
A high-quality copy of the film was being downloaded by hundreds of people each day via a website which uses the file-sharing computer program BitTorrent.
The website was subsequently taken down on Tuesday.
The availability of the film online will come as a blow to executives who co-ordinated a worldwide release of the film in an attempt to thwart piracy.
Low-quality copies of the film on DVD have also been reported for sale at a major traders' market in London.
Although it is not unusual for pirate copies of blockbuster films to appear on the internet soon after release, they are often of poor quality, filmed on a hidden videcamera by a cinemagoer.
The picture is often jerky, with poor sound, punctuated by ambient noise in the cinema.
But the copy available using BitTorrent appeared to be have made from a film print, and was in widescreen format with high quality sound.
A computer user with broadband internet access could download the film in about six hours.
The download also includes a teaser trailer for the third film in the sci-fi trilogy, The Matrix Revolutions.
Piracy, especially online, is one of the biggest concerns of the movie industry.
Jack Valenti, president of the Motion Picture Association of America, told BBC News Online earlier this year that digital piracy could become "debilitating" for the industry.
"Digital piracy has become a real menace," he said.
Despite the availability of pirate copies, The Matrix Reloaded has made more than $363.5m at the box office worldwide so far.