Napster's legal woes have done little to detract from the downloading of files over peer-to-peer networks.

More than 3.05 billion files were exchanged over four file sharing systems in August, according to new research.

This was more than the 2.79 billion files downloaded using Napster in February, the peak month for the once wildly popular file-sharing network.

FastTrack, accessible using the Morpheus, Kazaa and Grokster software applications, was the most popular system, though music-swapper Audiogalazy was a close second, according to research by Webnoize.

IMesh and Gnutella ranked third and fourth.

Matt Bailey, a Webnoize analyst who led the study, said music tracks still comprise the bulk of all downloads, although bootleg movies and software applications account for an ever-increasing portion of the file-sharing mix.

"Peer-to-peer users are getting more free content than they ever did through Napster," Bailey said.

"Despite the millions of dollars spent trying to kill off pirate networks, the popularity of peer-to-peer file sharing continues to grow."

He said for the recording and motion pictures industries, the peer-to-peer problem is about to go from bad to worse.

"After 15 months, other networks just stepped into Napster's place," Bailey said.

"The millions of dollars in legal fees was a waste of money for the recording industry."

A spokeswoman for the Recording Industry Association of America acknowledged there would be a certain amount of piracy online and offline. But she said: "We are not going to sue our way through the internet, as we do not believe that litigation is a business model."

The world's largest record labels, which include Universal Music, Sony Music, Warner Music, EMI Group and Bertelsmann's BMG, initially sued Napster in December 1999 for copyright infringement.