Spanish police arrested three suspected members of the so-called Anonymous group on Friday on charges of cyber-attacks against targets including Sony Corp's PlayStation Network, governments, businesses and banks.
Police alleged the three arrested "hacktivists" had been involved in a recent attack on Sony's PlayStation Network, as well as cyber-attacks on Spanish banks BBVA and Bankia and Italian energy group Enel SpA.
The arrests are the first in Spain against members of Anonymous following similar legal proceedings in the United States and Britain. Police told Reuters all three men were Spanish and in their 30s. One worked in the merchant navy.
Sony shocked gamers in late April by revealing that hackers had stolen personal information from the accounts of 77 million users of its online video-games network.
A week later, it said hackers had stolen data from another 25 million users of its computer games system. Sony's PlayStation Network was crippled for a month as the company tried to find and fix the problem.
Anonymous, a loose grouping of activists which has carried out cyber attacks on organizations including Sony in the past, said at the time it was not responsible for those attacks and had no interest in stealing credit-card details.
Its members describe themselves as internet freedom fighters and have previously brought down websites of the Church of Scientology as well as Amazon.com Inc, Mastercard Inc and others they saw as hostile to WikiLeaks.
Their current targets include the Turkish government, in a protest against internet censorship. Anonymous members on Friday called for attacks on Spain.
Spanish police said the accused, who were arrested in Almeria, Barcelona and Alicante, were guilty of coordinated computer hacking attacks from a server set up in a house in Gijon in the north of Spain.
Mark Rasch, former head of the U.S. Justice Department's cyber crimes division, said he would not be surprised if Anonymous turned out to be linked to the Sony data breach given they had publicly criticized the company over its intellectual property rights.
"It was a logical place to look," he said.
The Spanish police said members of Anonymous, known for wearing Guy Fawkes masks made popular by the graphic novel "V for Vendetta," had also hacked government sites in Egypt, Algeria, Libya, Iran, Chile, Colombia and New Zealand.
"They are structured in independent cells and make thousands of simultaneous attacks using infected 'zombie' computers worldwide. This is why NATO considers them a threat to the military alliance," the police said in a statement.
"They are even capable of collapsing a country's administrative structure."
The police did not rule out further arrests.