A website accused of directing users to pirated films, music and software has been closed by Swedish police.
BitTorrent allows people to share large files across the internet
More than 50 law enforcement officials raided 10 locations, confiscating the computers and detaining three people.
ThePirateBay.org had described itself to be the largest search index for BitTorrent, a system used for sharing large files across the internet.
The entertainment industry welcomed the action against a site it argued was a major source of music and film piracy.
The people behind The Pirate Bay argued they were not breaking the law.
They maintain that the site's function was to direct users towards the files that they search for and manage the uploads and downloads. The website itself did not hold any copyright files themselves.
The legality of the website has not been tested in Swedish courts.
Stockholm police carried out the raids in 10 locations and said they had detained three people.
In a statement the police said the people had been taken in for questioning "on suspicion of breaking copyright law or abetting the breaking of copyright law".
A statement on ThePirateBay.org website questioned the reason behind the police action.
"The necessity for securing technical evidence for the existance (sic) of a web-service which is fully official, the legality of which has been under public debate for years and whose principals are public persons giving regular press interviews, could not be explained," said the statement.
"Asked for other reasoning behind the choice to take down a site, without knowing wether (sic) it is illegal or not, the officers explained that this is normal."
It said it planned to up and running again within a few days.
The closure is the latest move in a country where file-sharing has become a divisive topic.
In the past, the country had been singled out for criticism by Hollywood. With no law banning file-sharing, Sweden had become a hotbed of piracy where films, music and software were readily swapped.
Last year, it outlawed the unauthorised downloading of copyrighted movies and music in an attempt to curb piracy.
The Pirate Bay became a dominant player in tracking BitTorrent files when another search index, SuprNova.org met its demise in late 2004.
SuprNova.org, closed after a relentless campaign by the entertainment industry to close its operations.
Until now, the Pirate Bay seemed to have resisted similar action. Supporters started their own political party, to run in this year's elections, campaigning on copyright issues.
Groups like the IFPI, which represents the recording industry worldwide, welcomed the police action.
"This is a very important development for Sweden, a country with a fantastically rich music culture, yet which has more recently acquired a reputation as a haven for copyright infringement," said John Kennedy, CEO of the IFPI.
"The Pirate Bay has damaged the legitimate music industry on an international scale."