The British music industry stepped up its campaign against illegal file-sharing on Monday by demanding that two Internet service providers suspend 59 accounts it believes are being used to swap copyrighted songs.

The British Phonographic Industry trade group called on Cable & Wireless and Tiscali to join a crusade against consumer practices that have undermined music companies in recent years.

"We have said for months that it is unacceptable for ISPs to turn a blind eye to industrial-scale copyright infringement," BPI Chairman Peter Jamieson said in a statement.

"We are providing Tiscali and Cable & Wireless with unequivocal evidence of copyright infringement via their services," he added. "It is now up to them to put their house in order and pull the plug on these people."

A C&W spokeswoman said policies for its ISP Bulldog covered such matters and "would normally mean that any accounts used for illegal file-sharing are closed," though she declined to comment specifically about the evidence or customers cited by BPI.

"We will take whatever steps are necessary to put the matter right," she added.

Tiscali said it does not automatically suspend customer accounts on request, but does so on occasion following an investigation.

"We are reviewing the information they have provided and will respond appropriately," the company said.

The BPI, which has won court verdicts against consumers illegally uploading songs and settled with others in the past, said it gathered evidence against the accounts by using the file-sharing networks themselves.

It added that it had identified 42 C&W IP addresses and 17 from Tiscali that have been used to upload significant amounts of music under copyright. The BPI said it could identify the service being used but that only the ISPs know to whom the addresses belong.

"Both Tiscali and Cable & Wireless state in their terms of use for subscribers that Internet accounts should not be used for copyright infringement," BPI's general counsel Roz Groome said. "We now invite them to enforce their own terms of use."

The U.S. music industry tried to force telecoms companies to reveal the names of their customers allegedly using file-sharing networks to illegally share songs, but it lost a legal battle to do so in 2004.

Record companies must now first obtain court-approved subpoenas against the unknown holders of IP addresses, which then can be served on ISPs, allowing consumers to challenge the claims before their names are disclosed.