Widening its legal assault on copyright infringement, the Motion Picture Association of America (MPAA) has filed seven lawsuits in US federal courts against search engines and newsgroups affiliated with P-to-P (peer-to-peer) networks.

The suits are the first that the MPAA has filed against these kinds of sites, which may not store copyright films but contain instructions on how to download them, the industry group said. The sites are "sophisticated enterprises" that encourage people to download content illegally, according to the MPAA.

Some of the sites hunt for content on widely used P-to-P platforms, such as eDonkey and BitTorrent. They include TorrentSpy.com, which the MPAA said is the most popular site for obtaining content using Torrent software. The site offers 160,000 movies, songs and TV shows, the MPAA said.

A cursory search at TorrentSpy.com uncovered the new film release 'Walk the Line', about the life of country-music star Johnny Cash, along with a 'torrent', or piece of metadata that instructs a downloading program where to receive the file. The install notes read: "Burn and See - Enjoy!"

Last week, a 25-year-old man was charged with copyright infringement in the US after MPAA officials duped him in a chatroom into posting 'Walk The Line' on a protected server they had set up. The copy of the movie had been intended for an Oscar film awards juror who failed to receive it by mail.

Other affiliates of the Torrent network targeted in the lawsuits include Isohunt.com, BTHub.com, Torrentbox.com and NiteShadow.com. The MPAA also sued Ed2k-It.com, associated with eDonkey, and three membership-based websites: NZB-Zone.com, BinNews.com and DVDRs.net, it said.