LOS ANGELES -- The recording industry has tapped into two Internet file-swapping services and is flashing messages to music traders warning them they're breaking the law.

"COPYRIGHT INFRINGEMENT WARNING," the message reads. "When you break the law, you risk legal penalties. There is a simple way to avoid that risk: DON'T STEAL MUSIC."

At the same time, the industry is collecting the user names of people suspected of illegally offering copyright material with the file-sharing services Kazaa and Grokster, but it doesn't intend to pursue legal action, said Recording Industry Association of America President Cary Sherman.

Sherman, who announced the effort Tuesday, called it "educational" and said "there's no enforcement connected to this."

Kazaa owner Sharman Networks likened the RIAA campaign to spam meant to confuse users. Grokster Ltd. President Wayne Rosso called it "a death rattle."

"It doesn't bother us, because we are very anti-copyright infringement anyway," Rosso said. "They think they're harassing us. No. What they're doing is declaring war on our users."

The tactic is the latest in the industry's battle to curb the illegal duplication of copyright works, which it blames for a drop off in compact disk sales.

Last week, the industry lost a court battle against file-sharing services after a judge ruled that Grokster and StreamCast Networks Inc. are not responsible for illegal copying by their users. A similar lawsuit against Kazaa is pending.

Media analysts estimate that as many as 61 million Americans use Internet services such as Kazaa and Grokster to download copyright material.

The peer-to-peer software allows users to search other users' computers for song, movie and other types of files. It also allows users to contact each other through a text messaging feature.

Unlike Napster, the pioneer file-sharing service ordered shut by the courts, Grokster and StreamCast say they only provide software and technical assistance rather than actually hosting users' files on servers.

The RIAA was able to find Grokster and Kazaa users' screen names through a computer application designed to work with the peer-to-peer software that allows automated searches of 100-200 of the most popular or most traded song titles on the services.

The message the RIAA sent warns users that they are not anonymous, can be easily identified and are at risk for legal penalties. It suggests the user disable the file-swapping software.

Grokster, based in Nevis, West Indies, will not try to block the RIAA from contacting its users, Rosso said. He said users that want to stop the messages can change their software settings to block text messages.

The RIAA, meanwhile, plans to send out about 1 million messages per week, Sherman said.

Only Kazaa and Grokster users who have their peer-to-peer software set for file sharing are being targeted at this point, he said. No decision has been made on whether to expand the campaign to users of other file-sharing services, Sherman said.

In a separate action, the RIAA has sued four college students who allegedly offered more than 1 million recordings over the Internet, demanding damages of $150,000 per song.

On the Net:

Recording Industry Association of America: http://www.riaa.org/

Kazaa.com: http://www.kazaa.com/us/index.php

Grokster.com: http://www.grokster.com