Joint raids by police in Belgium and Switzerland have shut down a popular file-sharing server.
The Razorback server held an index of pirated movies and albums
The Razorback2 server was part of the Edonkey file-sharing network and was used by a third of the system's users.
The server held an index of 170 million pirated files, said the Motion Picture Association of America (MPAA).
In the raids, the server's Swiss owner was arrested and the Razorback2 machines were seized from a Brussels-based hosting firm.
The statement from the MPAA said Razorback2 was one the largest of the 200 or so index servers on the Edonkey file-sharing network. Users consult these to track down files.
It hosted one of Edonkey's most widely used indexes of pirated copies of movies, games, TV programmes, music tracks and software.
The joint raids are the latest move against the Edonkey network. Previously raids have shut down many of the file-sharing network's most popular servers in the US.
Unlike many other file-sharing servers, Razorback2 was run as a business and generated cash for its owners via donations and advertising.
In the statement Dan Glickman, MPAA chairman, said: "This is a major victory in our fight to cut off the supply of illegal materials being circulated on the internet via peer-to-peer networks."
It is unclear what effect the shutting down of the Razorback2 server will have on overall file-sharing figures.
Studies of the different file-sharing networks show that the numbers of people using Edonkey is on the increase. It has become the dominant network in South Korea, Italy, Germany and Spain.
However, following raids and shutdowns, many file-sharers simply move to other networks such as BitTorrent or have turned to older systems such as Usenet.
Notes posted on discussion groups by Edonkey users following the raid show that the number of people on the Edonkey network was back to normal a few hours after the server was shut down.