Filed at 7:04 p.m. ET

ALBANY, N.Y. (AP) -- Saying the file-swapping service Madster appears to contribute to copyright infringement ``on a massive scale,'' a federal judge granted a preliminary injunction against the service Wednesday.

The order issued from U.S. District Court in Chicago is a victory for record companies, which claim Madster violates copyright law just as Napster had before it. More than two dozen record and other media companies are involved in the litigation against the Albany-based service formerly know as Aimster.

``At issue is a service whose very raison d'etre appears to be the facilitation of and contribution to copyright infringement on a massive scale,'' Chief Judge Marvin Aspen wrote in his order granting the companies' request for a preliminary injunction.

Aspen gave the companies suing Madster until next week to propose language for a ``narrowly tailored'' injunction that would end copyright infringement ``while allowing non-infringing uses of the Aimster system, if any, to continue.''

Madster founder Johnny Deep said he had not seen Aspen's opinion. But he said he didn't think there was a lot of copyrighted material shared on Madster. He said he didn't know of a way to block only copyrighted files because the transferred material is encrypted.

``We couldn't possibly filter, at least that I know of,'' he said.

The Recording Industry Association of America, a trade group for the record companies, said all Madster's arguments were rejected by the judge.

``This unequivocal ruling today underscores that companies and individuals will not be permitted to build a business on music they do not own and will be held responsible for their actions,'' said RIAA Chairman Hilary Rosen.

Attorneys for the record and media companies plan to promptly submit proposed injunction language to the Chicago court. They also plan to file a motion for summary judgment next week in Los Angeles federal court in a pending suit against several other file-sharing companies.

While acknowledging they don't know how many files shared on Madster are copyrighted, an RIAA official said 87 percent of Napster's former content was infringing and it is probably about the same.

Madster started as a free service that allows users to trade music and other types of files over the Internet. The site now offers a $4.95-a-month ``Club Madster'' subscription service that offers file recommendations made by other members and other extras.

A series of suits and countersuits regarding Madster were consolidated in Chicago, although that litigation was stayed in March after bankruptcy filings were made by Deep and two companies involved in the service's operations. The recording companies are seeking damages.

A bankruptcy judge in Albany lifted the stay for the limited purpose of allowing plaintiffs to ask a federal judge in Chicago to decide on the preliminary injunction motion.

Madster dropped its old Aimster name as part of a settlement agreement with America Online.