Internet activists defied efforts Thursday to end their online assaults on companies seen as enemies of WikiLeaks, even as one Dutch teenager was arrested in the wave of cyber attacks.
U.S. Attorney-General Eric Holder said U.S. authorities are looking into cyber attacks on companies such as Amazon.com and others. "We are aware of the incidents," he said.
The 16-year-old boy was arrested by a high-tech crime unit in The Hague after allegedly admitting to attacks on the websites of two credit-card companies, MasterCard and Visa, the prosecution in the Netherlands said on its website.
The suspect, whose details were not disclosed, was believed to be part of a larger group of hackers under investigation that participated in so-called denial-of-service attacks, the prosecution said. Data and computer equipment were confiscated during his arrest.
The loosely organized campaign to avenge WikiLeaks against those who have obstructed its operations, calling itself Operation Payback, has already temporarily brought down the websites of credit-card giants Visa and MasterCard, and of the Swedish government.
A succession of U.S. institutions has withdrawn services from WikiLeaks after the website published thousands of sometimes embarrassing secret U.S. diplomatic reports that have caused strains between Washington and several allies.
In Moscow, Russian Prime Minister Vladimir Putin said the arrest of WikiLeaks founder Julian Assange showed the West was hypocritical in its criticism of Russia's record on democracy.
When asked about leaked U.S. diplomatic cables that cast him as Russia's "alpha-dog" ruler of a corrupt bureaucracy, Mr. Putin questioned whether the U.S. Foreign Service was a "crystal clean source of information."
WikiLeaks activists instructed their followers on Thursday to mount a distributed denial-of-service attack on a PayPal website that manages the integration of the company's payment-processing technology with independent online merchant websites. Paypal is a subsidiary of eBay.
Online retail and Web-hosting powerhouse Amazon last week stopped hosting WikiLeaks's website, and on Thursday it briefly became the main target of the pro-WikiLeaks campaigners - before they admitted it was too big for them, for the moment.
The activists said they would instead attack PayPal, which has suspended the WikiLeaks account that the organization had used to collect donations.
Facebook said it had removed the activists' Operation Payback page on Thursday because it was promoting a distributed denial-of-service attack - a form of freezing websites by bombarding them with requests that is illegal in many countries.
The campaign also disappeared briefly from Twitter before reappearing in a different guise. Twitter declined to comment.
In an online letter, Anonymous, a loose-knit group, said its activists were neither vigilantes nor terrorists. It added: "The goal is simple: Win the right to keep the Internet free of any control from any entity, corporation or government."