Copies of two new films starring Tom Cruise and Jack Nicholson that were sent on video to Oscars voters have been found to download on the internet.
The Last Samurai has become the second film to go online
Nicholson comedy Something's Gotta Give and Cruise's The Last Samurai ended up online despite a pledge by award voters to ensure their videos were not copied.
Film studios banned the distribution of preview tapes for fear of piracy.
But they relaxed the rules for the Oscars - as long as voters signed an agreement to keep their copies safe.
The ban, which also covered all other award ceremonies, was later overturned by a judge after some producers said it would hurt their chances to win awards.
The leaks have now prompted an investigation by Oscars organisers The Academy of Motion Picture Arts and Sciences.
Something's Gotta Give stars Jack Nicholson and Diane Keaton
The encoded preview tapes, known as "screeners", can be traced back to the individual they were sent out to.
The academy said The Last Samurai studio Warner Bros had not identified the intended recipient of the tape that ended up online.
All 5,803 eligible Oscar voters had been required to sign forms promising they would not make their copies available over the internet.
Explaining the ban, Motion Picture Association of America president Jack Valenti said: "The impact and growing threat of piracy is real and must be addressed wherever it appears."