Officers from Britain's National Hi-Tech Crime Unit (NHTCU) made three arrests on Thursday as part of an international crackdown on Internet software piracy.
The men were detained at addresses in Belfast, Manchester and Sheffield, and are suspected of being part of a worldwide conspiracy that copied thousands of computer programs, film and music, and distributed them online.
The police seized a wide range of cracked software, as well as seven computers and 100 CD copiers.
"We were struck by the sheer quantity of material across all media, from business software to Sony PlayStation," said a NHTCU spokesperson.
No charges have yet been brought again the three, who have been released on bail.
The UK arrests were part of a global action dubbed "Operation Fastlink" that involved a total of 10 countries.
The operation specifically targeted an underground software piracy ring called Fairlight. This "warez" group has allegedly disseminated pirated copies of computer software, games, movies and music on the Internet.
Members of such groups may distribute material to "select clientele" over secure servers, and those files eventually end up on an Internet Relay Chat network or a peer-to-peer file-sharing service, according to the US Department of Justice.
Operation Fastlink is the second major piracy crackdown to involve the NHTCU. In 2001, it took part in an operation against an alleged piracy ring known as "drink or die", which was suspected of pirating millions of pounds worth of copyrighted software, games, music and digital videos.
CNET News.com's Jim Hu contributed to this report