LIMA, Peru -- People identifying themselves as activists in the Anonymous hacker movement said Wednesday it wasn't technical prowess but police infiltration that yielded 25 arrests in a sweep in Europe and South America.
In conversations in an online chat room where Spanish-speaking activists in the Americas and Spain regularly gather, they said nearly all of those arrested had been active on a single website used by the group.
Among those detained were a Spaniard known by the online nickname "Pacotron" or "Thunder," according to Spanish police and a communique issued by Anonymous Iberoamerica, which said he lives in Malaga.
The statement by the loosely organized collective's Spanish-language branch identified another of those arrested as a Spaniard known as "Troy" who it said owned computer servers in "such distant places as Slovakia and Romania."
Interpol, which announced the arrests Tuesday, did not say how it encountered the 25 suspects, who it says were involved in cyberattacks originating from Argentina, Chile, Colombia and Spain that targeted sites including Colombia's defense ministry and presidency and Chile's Endesa electricity company and national library.
Activists encountered in the chat room said some of those arrested belonged to a group of hackers called Sector404 while others were unsophisticated activists who took part in denial-of-service attacks, which overwhelm websites with data requests.
"The GREAT majority of those implicated were people inhabiting the servers of anonworld.info, something that disconcerts us," said the activist "Skao," who identified herself as a law student.
In the communique released on its blog, Anonymous Iberoamerica said the 25 were snared not through "inteligence work or informatics strategy" but rather through "the use of spies and informants within the movement."
The activists said many of those arrested had been careless, leaving digital tracks.
A spokeswoman for Chile's chief prosecutor, Marlis Pfeiffer, told The Associated Press on Wednesday that authorities had released the five people arrested there in the sweep, two of whom were 17-year-olds. Anonymous Iberoamerica said three of them were computer science students, one a programmer and one a Colombian.
Pfeiffer said investigators were examining computers confiscated from the five to determine if criminal charges will be filed but were encountering difficulties, presumably encrypted data.
An Argentine police official said Wednesday that 10 adults were still being detained. The official said he had no further information and spoke on condition he not be further identified. Anonymous Iberoamerica said those arrested in Argentina included Colombians and that many were minors.
The arrests followed an investigation begun in mid-February and also led to the seizure of 250 items of IT equipment in 15 cities, according to Interpol, the international police agency that announced them.
Anonymous activists deface websites, carrying out denial-of-service attacks and publish data obtained in computer break-ins.
They are engaged in a number of political causes, including opposition to the global clampdown on file-sharing sites and defense of the secret-spilling site WikiLeaks. The Vatican has also been a target.
In Brazil, Anonymous hacktivists attacked nine banks last month.
Elsewhere in Latin America, they have targed government agencies and ministries they claim are corrupt.
"We hope you understand and reveal that we are not hackers on steroids. We are activists and what happens in the world matters to us," said Skao.
Authorities in Europe, North America and elsewhere have made dozens of arrests of Anonymous activists. In response, the group has increasingly attacked law enforcement, military and intelligence-linked targets.
Anonymous has no real membership structure. Hackers, activists, and supporters can claim allegiance to its freewheeling principles at their convenience, so it's unclear what impact the arrests will have.
Associated Press writer Raphael Satter in London contributed to this report.