Napster blamed as Madonna single leaks onto net

Large sections of Madonna's next single, the title track to forthcoming album Music, have appeared on the internet - much to her fury.

The veteran pop chanteuse, 41, had her new album pencilled in for a September/October release but this date is now said to be under threat as a reportedly "livid" Madonna considers her options.

Fan sites have made available downloads of between 30 seconds and three minutes sections of the unfinished single online, and fingers have been pointing at the controversial Napster MP3 file-sharing system.

A statement issued by Madonna's US manager said: "This music was stolen and was not intended for release for several months. It is still a work in progress. Ultimately those sites that offered a download of Madonna's music are violating her rights as an artist."

Meanwhile, Madonna's record label publisher Warner Brothers has threatened that "any website that does not remove our copyrighted material runs the risk of civil and criminal prosecution".

A Warner spokesman would make no comment on how the music may have been leaked originally, saying only that the firm expected website owners who have included this material on their site to comply with its request to prevent further downloads.

Napster is already under fire from rap star Dr Dre and rockers Metallica but Madonna is easily the biggest name to support the music industry's growing campaign against Napster.