Interpol said Tuesday that 25 people suspected of being affiliated with the Anonymous hacking group were arrested in four countries in South America and Europe, with authorities seizing IT equipment, payment cards and cash.
The arrests were made across 15 cities in Argentina, Chile, Columbia and Spain, Interpol said in a news release. They followed an investigation called "Operation Unmask" that began in mid-February following cyberattacks directed at Columbia's Ministry of Defense and the president's website, and Chile's Endesa electricity company and its national library.
Authorities searched 40 premises and seized 250 items including computer equipment and mobile phones. An investigation continues into how the alleged hackers' activities were funded, Interpol said.
A prominent Twitter account linked to Anonymous, AnonOps, hinted that the group had been attacking Interpol's website in retaliation on Wednesday. One tweet read, "Tango Down II 404 Interpol."
Anonymous often conducts distributed denial-of-service (DDoS) attacks against websites, which involves bombarding a site with so many traffic requests it becomes unavailable.
The arrests mark one of the biggest roundups so far of people allegedly affiliated with Anonymous, a decentralised group that undertakes hacking campaigns to protest policies and organizations it opposes.
Separately this week, Wikileaks on Tuesday began releasing some 5 million emails from the global intelligence analyst firm Stratfor Global Intelligence, which was targeted by Anonymous last December.
And earlier this month, Anonymous took credit for recording a conference call between U.S. and British law enforcement agents investigating the group. They posted a 17-minute recording of the call on YouTube.