The US government has begun a crackdown on users of peer-to-peer (P2P) networks, seizing computer equipment in raids at five addresses and one internet service provider in three US states.

'Operation Digital Gridlock' has targeted the alleged illegal file sharing of copyrighted material over five Direct Connect P2P networks known as The Underground Network.

Authorities claimed that, to join the group, prospective members had to offer between 1GB and 100GB of material for others to share.

Federal agents have already executed six search warrants, seizing computer equipment thought to contain illegally copyrighted movies, games and music.

"The execution of today's warrants disrupted an extensive peer-to-peer network suspected of enabling users to traffic illegally in music, films, software and published works," said attorney general John Ashcroft in a statement.

"The Department of Justice is committed to enforcing intellectual property laws, and we will pursue those who steal copyrighted materials even when they try to hide behind the false anonymity of peer-to-peer networks."

US authorities claim that $19bn is lost annually to US firms through the illegal reproduction and distribution of movies, software, games and music.

"Today we are sending a clear message that federal law enforcement takes piracy seriously," said US attorney Kenneth L. Wainstein.

"It is illegal to trade in copyright-protected materials on the internet; this is theft, plain and simple."

The maximum penalty for criminal copyright infringement for a first-time offender is five years imprisonment and a fine of $250,000.