The Recording Industry Association of America (RIAA) has filed a new round of lawsuits against file-sharers.

The 751 new lawsuits bring the total number of such lawsuits in the US to about 17,100 since September 2003. The RIAA has settled with about 3,800 people, a spokeswoman said.

The lawsuits come a day after a study was released saying US residents' use of file-sharing services dropped late this year. The US Supreme Court in June ruled that entertainment companies could sue P-to-P services Grokster and Morpheus for copyright infringement, and The NPD Group study said the number of US households downloading at least one unauthorised song using such software dropped 11 per cent between June and October.

Grokster shut down in November as part of a settlement with the RIAA and Motion Picture Association of America. The Grokster website says it continues to work on relaunching with a "safe and legal" service.

In October, members of 5.7 million US households downloaded at least one unauthorised song using P-to-P services, according to NPD, which tracks PC usage from 11,000 households. That's down from 6.4 million in June, NPD said.

NPD had observed a growing use of P-to-P software to download music in 2004 and early 2005. Such use peaked in the fourth quarter of 2004, the analysts said.

NPD music industry analyst Russ Crupnick said: "If this trend continues throughout the remainder of the fourth quarter 2005 and into next year, it would signify a solid victory in the music industry's efforts against illegal music file sharing in the US."

In the new RIAA lawsuits, students at Drexel University, Harvard University, and the University of Southern California were among those sued. Users of the LimeWire and Kazaa P-to-P software packages were also among those sued, the RIAA said.

In addition to the 751 lawsuits filed against unnamed defendants, the RIAA also announced Thursday that it had identified 105 defendants from past "John Doe" lawsuits and filed lawsuits against those people. Residents of Arizona, Connecticut, Georgia, Illinois, Massachusetts, Michigan, North Carolina, Nebraska, New Jersey, New York, Texas and Wisconsin were named in those lawsuits.

The RIAA continues to see the lawsuits as "one component" of an effort to educate people about copyright infringement and stop the unauthorised downloading of music, said RIAA spokeswoman Jenni Engebretsen. "Without question, the lawsuits have helped to arrest the use of illegal peer-to-peer services," she said.