MADRID >> Spanish police have arrested three suspected computer hackers who allegedly belonged to a loose-knit international activist group that attacked corporate and government websites around the world, authorities said Friday.

National Police identified the three as leaders of the Spanish section of a group that calls itself “Anonymous.” All three are Spaniards aged 30 to 32, said Manuel Vazquez, chief of the police’s high-tech crime unit.

A computer server in one of their homes was used to take part in cyber attacks on targets including two major Spanish banks, the Italian energy company Enel and the governments of Egypt, Algeria, Libya, Iran, Chile, Colombia and New Zealand, Vazquez said.

His comments backtracked somewhat from an earlier police statement that said this server was used to actually execute the attacks. The three detainees have been released without bail but face a charge that is new in the Spanish penal code — disrupting a computer system, Vazquez said. He gave no details on what effect these attacks had.

In Spain, acting on their own, the three detainees staged cyber attacks on the website of Spain’s central electoral commission a few days before local and regional elections on May 22, that of the regional police force in the northeast Catalonia region and a major Spanish labor union.

The night before the election, the three men tried to shut down the web pages of Spain’s two main political parties and that of the Spanish parliament but were thwarted by police, Vazquez said.

“Anonymous is a network with a common idea, but it has loads of cells around the world. Using chats they agree to stage denial-of-service attacks on any page of any company or organization anywhere in the world,” Vazquez said, referring to a cyber-bombardment-like technique used to shut down an Internet page.

Vazquez said police were still analyzing computer files and other material but have no record of the three Spaniards having obtained sensitive data.

Vazquez said members of Anonymous use a lot methods for hiding their identity.

The statement said the only other countries to act against “Anonymous” so far are the United States and Britain. It attributed this what it called complex security measures that members use to protect their identity.

The suspects in Spain were arrested in Barcelona, the Valencia region and the southern city of Almeria.

Since October 2010, Spanish police specializing in cyber crime have analyzed more than two million lines of online chat and Internet pages until they finally zeroed in on the three suspects. Their names were not given.

In January, British police arrested five young males on suspicion of involvement in cyber attacks by Anonymous, which has backed WikiLeaks.

“Anonymous” has claimed responsibility for attacking the websites of companies such as Visa, Mastercard and Paypal, all of whom severed their links with WikiLeaks after it began publishing its massive trove of secret U.S. diplomatic memos.

“Anonymous” accused the companies of trying to stifle WikiLeaks and rallied an army of online supporters to flood their servers with traffic, periodically blocking access to their sites for hours at a time.

And in February, an Internet forum run by “Anonymous” directed participants to attack the websites of the Egyptian Ministry of Information and the ruling National Democratic Party.

In a Twitter post, the group claimed credit for taking down the ministry’s website and said the group was motivated by a desire to support Egyptian pro-democracy protesters.

— Jorge Sainz in Madrid contributed to this report.