Fourteen people were arrested for allegedly mounting a cyber attack on the PayPal website after it suspended the accounts of WikiLeaks.
Separately, FBI agents executed more than 35 search warrants around the country in a continuing investigation into coordinated cyber attacks against major companies and organisations.
As part of the effort, there were two arrests in the United States unrelated to the attack on the PayPal payment service. Overseas, a 16-year-old boy was arrested by Scotland Yard in south London, and there were four arrests by the Dutch National Police Agency, all for alleged cybercrimes.
In one case unrelated to PayPal and filed in New Jersey, a customer support contractor was charged with stealing confidential business information on AT&T's servers. The data was posted on a public file sharing site, and Lance Moore, 21, of Las Cruces, New Mexico, was accused of exceeding his authorised access to AT&T's servers in downloading thousands of documents and applications.
According to court papers, the documents the contractor uploaded were the same ones publicised last month by the computer hacking group Lulz Security, or LulzSec, which said it had obtained confidential AT&T documents and made them publicly available on the internet.
The 16-year-old detained in London is thought to be connected to LulzSec, according to a UK official familiar with the investigation.
A hacker with LulzSec did not immediately return a message seeking comment early today. The group's Twitter feed made no mention of any arrests, although "Sabu", a reputed member of the six-person collective, posted a message to the micro-blogging site saying the hackers could not confirm a report that one their own had been detained.
The cyberattacks on online payment service PayPal's website by the group called Anonymous followed the release by WikiLeaks in November of thousands of classified US State Department cables.
Anonymous is a loosely-organised group of hackers sympathetic to WikiLeaks. It has claimed responsibility for attacks against corporate and government websites worldwide.
The group also claims credit for disrupting the websites of Visa and MasterCard in December when the credit card companies stopped processing donations to WikiLeaks and its founder Julian Assange.
A federal indictment unsealed in US District Court in San Jose, California, says Anonymous referred to the cyberattacks on PayPal as "Operation Avenge Assange".
The 14 charged in the PayPal attack were arrested in Alabama, Arizona, California, Colorado, the District of Columbia, Florida, Massachusetts, Nevada, New Mexico and Ohio. They were aged between 20 and 42. The name and age of one of the 14 was withheld by the court.
The 20-year-old, Mercedes Renee Haefer, is a university student, and her lawyer, Stanley Cohen of New York, compared the case to the federal prosecution of former US defence analyst Daniel Ellsberg following his release in 1971 to The New York Times and other newspapers a Pentagon study of government decision-making about the Vietnam War.
The government said Haefer was also known as "No" and "MMMM".
"In the 18th century, people stood on street corners handing out pamphlets saying, 'Beware the all-powerful military and big government'," Mr Cohen said. "Some people listened. Some people walked away. Today, pamphleteers use the internet."
Mr Cohen compared the acts allegedly committed by his client and the others to civil disobedience. "The people being arrested are not being accused of acts of violence," he said.
In addition to Haefer, the government said those indicted in San Jose were Christopher Cooper, 23, also known as "Anthrophobic"; Joshua Covelli, 26, aka "Absolem" and "Toxic"; Keith Downey, 26; Donald Husband, 29, aka "Ananon"; Vincent Kershaw, 27, aka "Trivette", "Triv" and "Reaper"; Ethan Miles, 33; James Murphy, 36; Drew Phillips, 26, aka "Drew010"; Jeffrey Puglisi, 28, aka "Jeffer", "Jefferp" and "Ji"; Daniel Sullivan, 22; Tracy Valenzuela, 42; and Christopher Quang Vo, 22.
In the other non-PayPal case, Scott Arciszewski, 21, was arrested on charges of intentional damage to a protected computer. Arciszewski made his initial appearance in court in Orlando, Florida, yesterday.
According to the complaint, on June 21 Arciszewski allegedly accessed without authorisation the Tampa Bay InfraGard website and uploaded three files, then tweeted about the intrusion and directed visitors to a separate website containing links with instructions on how to exploit the Tampa InfraGard website.
InfraGard is a public-private partnership for critical infrastructure protection sponsored by the FBI, with chapters in all 50 states.
LulzSec, a spin-off group of Anonymous, has taken responsibility for attacks on Fox News and PBS, entertainment companies, including Sony and Nintendo, as well as local chapters of InfraGard and Arizona law enforcement.
The hackers earlier this week broke into The Sun newspaper's website and posted a bogus story claiming that media tycoon Rupert Murdoch had been found dead.
The group still says it is sitting on a cache of emails stolen from a server belonging to News International.