The group said in a statement on its Web site that federal authorities issued a court order requesting the computer equipment Thursday morning to United States-based Web hosting provider Rackspace. The hosting company subsequently handed over the Web servers, located in its London facility, to authorities, Independent Media Center (IMC) said.
Rackspace issued a terse comment on the issue, saying it responded to a subpoena in an investigation that did not originate in the United States.
"Rackspace is acting as a good corporate citizen and is cooperating with international law enforcement authorities," the company's statement read. "The court prohibits Rackspace from commenting further on this matter."
A spokeswoman for IMC said the group had not been told why it was the subject of an investigation.
"We don't know why it happened," said Hep Sano, a member of the IMC organization in San Francisco. "We did not receive a copy of the subpoena. Right now, we're trying to organize legal help to figure out what the procedure is."
She added that the group thinks the issue might be related to recent requests by the FBI asking that the site remove photos posted by IMC's Nantes affiliate, purportedly depicting Swiss undercover police.
An FBI representative in Texas, where Rackspace is based, did not return calls for comment.
The IMC site said the loss of the Web servers affected local independent media sites serving Ambazonia, Uruguay, Andorra, Poland, Western Massachusetts, Nice, Nantes, Lilles, Marseille (all France), Euskal Herria (Basque Country), Liege, East and West Vlaanderen, Antwerpen (all Belgium), Belgrade, Portugal, Prague, Galiza, Italy, Brazil, the United Kingdom and Germany.