The US record industry is employing new methods to counteract the growing phenomenon of unauthorised music files, according to reports.

Many large record labels have resorted to what is known as "spoofing"- hiring companies to distribute "decoy" music files that are empty or do not work, to make the work of file-sharing services more difficult.

The US music body, the Recording Industry Association of America (RIAA), has said the approach is "lawful and appropriate".

The RIAA is reportedly considering the new step of suing individual computer users for infringing music copyrights.

'Declining sales'

An unnamed record executive told Associated Press: "They're talking about suing individual users.

"It's one of many options to stop declining sales, but they haven't agreed yet whether to go forward or not."

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The moves are seen as a sign of the alarm felt by the record industry over falling sales.

In 2001, for the first time since CDs were introduced, world music sales fell by 5% in value.

The RIAA declined to comment on the reports, but a move to suing individuals would spark fierce debate among record labels, who in the past have been reluctant to sue individual users for fear of losing customers.

Phil Leigh, analyst with Raymond James, said: "Launching a campaign of lawsuits against file swappers escalates the war against those who want online music. It invites retaliation."

Distributing "decoy" files is likely to be only slightly less controversial, but an RIAA spokesman defended the idea.

"Spoofing is just one example of a lawful and appropriate self-help measure available to the labels to respond to the growing problem of peer-to-peer network piracy.

'Passionate'

"It also happens to confirm the adage 'you get what you pay for,'" said the spokesman.

But Mr Leigh said that the record labels must shoulder some of the blame for the internet piracy problem.

"If the labels fail to provide a viable licensed alternative, they're likely to continue battling a vast army of computer-savvy youthful volunteers who are passionate about music in a digital format," said Leigh.

To date, MusicNet and Pressplay, the online initiatives of the "big five" music majors - EMI, Sony, BMG, Warner and Universal - have been seen as an unattractive alternative to unauthorised services.