The music industry has won a victory in its battle against internet piracy after a US court ordered a telecommunications firm to identify a customer who allegedly illegally downloaded music.

This case will have a chilling effect on private communications, such as e-mail, surfing the Internet or sending files between private parties Verizon Communications

US District Judge John Bates said the company, Verizon Communications, must comply with a subpoena issued by the Recording Industry Association of America (RIAA).

The RIAA's president, Cary Sherman, said the ruling validated their decision to pursue individuals accused of illegal downloading under a 1998 digital-copyright law.

But Verizon said it would appeal against the ruling, arguing that it violated privacy.

Experts say that the ruling means that recording companies will be able to track down consumers using internet file-sharing programmes more easily, and press for civil lawsuits or criminal prosecution.

'Legitimate alternatives'

The RIAA used the Digital Millennium Copyright Act against the user, who allegedly downloaded more than 600 songs from the Internet in one day.

CD copying, or burning, is an increasing 'threat' to sales

Verizon argued that the law only applied to material stored on the company's network, not files transmitted over it.

But the RIAA successfully argued that the law applied to all the material either stored on or transmitted over internet providers' networks.

"The illegal distribution of music on the internet is a serious issue for musicians, songwriters and other copyright holders," RIAA's president said in a statement.

"The record companies have made great strides in addressing this problem by educating consumers and providing them with legitimate alternatives."

'Chilling effect'

Verizon - who said it would not immediately identify the customer - said the ruling would have serious ramifications for the future growth of the internet.

"This case will have a chilling effect on private communications, such as e-mail, surfing the internet or sending files between private parties," it said in a statement.

"Verizon is not attempting to shield customers who break copyright laws.

"We are, however, seeking to protect the fundamental privacy and due process rights that should be afforded to our customers and all Internet users."

The music industry - whose total sales fell by 9% last year to $30.3bn - is facing the huge problem of tracks being downloaded free of charge from the internet.

Two years ago, firms succeeded in shutting down the free music website Napster, but many similar sites have replaced it since.