25 suspected members of the Anonymous hacker movement have been arrested in police raids across Europe and South America.
International police agency Interpol said the arrests in Argentina, Chile, Colombia and Spain were carried out by officers working under the support of Interpol's Latin American Working Group of Experts on Information Technology Crime.
The suspects, aged between 17 and 40, are believed to have planned co-ordinated cyber-attacks against institutions including Colombia's defence ministry and presidential websites, Chile's Endesa electricity company and national library, as well as other targets.
Yesterday's arrests followed an investigation in mid-February which also led to the seizure of 250 items of IT equipment and mobile phones in searches of 40 premises in 15 cities, Interpol said.
Police in Spain announced the arrest of four suspected Anonymous hackers in connection with attacks on Spanish political party websites. These four were among the 25 announced by Interpol.
A National Police statement said two servers used by the group in Bulgaria and the Czech Republic had been blocked.
It said the four included the alleged manager of Anonymous' computer operations in Spain and Latin America, who was identified only by his initials and the aliases "Thunder" and "Pacotron".
The four are suspected of defacing websites, carrying out denial-of-service attacks and publishing data on police assigned to the royal palace and the premier's office online.
Interpol, based in Lyon, France, has no powers of arrest or investigation but it helps police forces around the world work together, allowing intelligence sharing.
Anonymous, whose genesis can be traced back to a popular US image messaging board, has become increasingly politicised amid a global clampdown on music piracy and the international controversy over the secret-spilling site WikiLeaks, with which many of its supporters identify.
Authorities in Europe, North America and elsewhere have made dozens of arrests, and Anonymous has increasingly attacked law enforcement, military and intelligence-linked targets in retaliation.
One of Anonymous' most spectacular coups was secretly recording a conference call between US and British cyber-investigators tasked with bringing the group to justice.
Anonymous has no real membership structure. Hackers, activists, and supporters can claim allegiance to its freewheeling principles at their convenience, so it is unclear what impact the arrests will have.
Some internet chatter appeared to point to a revenge attack on Interpol's website, but the police organisation's home page was operating normally last night.
One Twitter account purportedly associated with Anonymous' Brazilian wing said the sweep would fail.
"Interpol, you can't take Anonymous," the message read. "It's an idea."
In Chile's capital Santiago, Subprefect Jamie Jara said authorities arrested five Chileans and a Colombian. Two of the Chileans were 17.
Prosecutor Marcos Mercado, who specialises in computer crime, said the suspects were charged with altering websites, including that of Chile's National Library, and engaging in denial-of-service attacks on websites of the electricity companies Endesa and Hidroaysen. The charges carry a penalty of 541 days to five years in prison.
General Carlos Mena, commander of Colombia's Judicial Police, said no-one was arrested in Colombia, but some Colombians had been arrested elsewhere, including Chile. He could not confirm a report that one of those arrested in Argentina may have been from Colombia.
Gen Mena did hint that there might be arrests in Colombia, saying other nations had been providing information and Colombian authorities were investigating.
"You have to leave them alone, so when we have all the evidence and the prosecutor makes the decision, we will be all over it and capturing them," he said.
No official statements had been released in Argentina. An Argentine media website based its story on the Interpol statement, which it quoted as saying that 10 people were arrested in Argentina.