WASHINGTON (June 25) - The embattled music industry disclosed plans Wednesday for an unprecedented escalation in its fight against Internet piracy, threatening to sue hundreds of individual computer users who illegally share music files online.

The Recording Industry Association of America, citing significant sales declines, said it will begin Thursday to search Internet file-sharing networks to identify music fans who offer ``substantial'' collections of MP3 song files for downloading.

It expects to file at least several hundred lawsuits seeking financial damages within eight to 10 weeks.

Executives for the RIAA, the Washington-based lobbying group that represents major labels, would not say how many songs on a user's computer might qualify for a lawsuit. The new campaign comes just weeks after U.S. appeals court rulings requiring Internet providers to identify subscribers suspected of illegally sharing music and movie files.

The RIAA's president, Cary Sherman, said tens of millions of Internet users of popular file-sharing software after Thursday will expose themselves to ``the real risk of having to face the music.'' He said the RIAA plans only to file lawsuits against Internet users in the United States.

``It's stealing. It's both wrong and illegal,'' Sherman said. Alluding to the court decisions, Sherman said Internet users who believe they can hide behind an alias online are mistaken. ``You are not anonymous,'' Sherman said. ``We're going to begin taking names.''

Shopping at a Virgin Megastore in San Francisco, Jason Yoder was planning to delete file-sharing software he uses from his home computer because of the new lawsuit threat. He acknowledged using the Internet recently to find a copy of a rare 1970s soul recording, but he agreed that illegal downloads should be curtailed.

``It's sort of like a serial drunk driver has to have their license taken away at some point,'' said Yoder, 30.

Sharman Networks Ltd., which makes the popular Kazaa software and operates one of the world's largest file-sharing networks, said in a statement, ``It is unfortunate that the RIAA has chosen to declare war on its customers by engaging in protracted and expensive litigation.'' Sharman said it was interested in a business relationship with music labels and could protect their songs from illegal downloads using technology.

Country songwriter Hugh Prestwood, who has worked with Randy Travis, Trisha Yearwood and Jimmy Buffett, likened the RIAA's effort to a roadside police officer on a busy highway.

``It doesn't take too many tickets to get everybody to obey the speed limit,'' Prestwood said.

Critics accused the RIAA of resorting to heavy-handed tactics likely to alienate millions of Internet file-sharers.

``This latest effort really indicates the recording industry has lost touch with reality completely,'' said Fred von Lohmann, a lawyer for the Electronic Frontier Foundation. ``Does anyone think more lawsuits are going to be the answer? Today they have declared war on the American consumer.''

Sherman disputed that consumers, who are gradually turning to legitimate Web sites to buy music legally, will object to the industry's latest efforts against pirates.

``You have to look at exactly who are your customers,'' he said. ``You could say the same thing about shoplifters - are you worried about alienating them? All sorts of industries and retailers have come to the conclusion that they need to be able to protect their rights. We have come to the same conclusion.''

Mike Godwin of Public Knowledge, a consumer group that has challenged broad crackdowns on file-sharing networks, said Wednesday's announcement was appropriate because it targeted users illegally sharing copyrighted files.

``I'm sure it's going to freak them out,'' Godwin said. ``The free ride is over.'' He added: ``I wouldn't be surprised if at least some people engaged in file-trading decide to resist and try to find ways to thwart the litigation strategy.''

The entertainment industry has gradually escalated its fight against piracy. The RIAA has previously sued four college students it accused of making thousands of songs available for illegal downloading on campus networks. But Wednesday's announcement was the first effort to target users who offer music on broadly accessible, public networks.

The Motion Picture Association of America said it supported the efforts, but notably did not indicate it plans to file large numbers of civil lawsuits against Internet users who trade movies online.

MPAA Chief Jack Valenti said in a statement it was ``our most sincere desire'' to find technology solutions to protect digital copies of movies.

Rep. Howard Berman, D-Calif., who has proposed giving the entertainment industry new powers to disrupt downloads of pirated music and movies, said the RIAA's actions were overdue. ``It's about time,'' Berman said in a statement. ``For too long ... file-traffickers have robbed copyright creators with impunity.''

The RIAA said its lawyers will file lawsuits initially against people with the largest collections of music files they can find online. U.S. copyright laws allow for damages of $750 to $150,000 for each song offered illegally on a person's computer, but Sherman said the RIAA will be open to settlement proposals from defendants.