WikiLeaks crackdown sparks web war
Skirmishes raged across cyberspace between WikiLeaks supporters and the companies they accuse of trying to stifle the group, with websites on both sides of the battle line taken out of service or choked off by attacks.
Meanwhile the United Nations' human rights high commissioner voiced alarm over moves by officials and corporations to cut off WikiLeaks' funding and starve it of server space - describing them as "potentially violating WikiLeaks' right to freedom of expression".
Navi Pillay also expressed surprise at the scale of the online attacks that have targeted major American financial players - in some cases denying access to their websites for hours at a time.
"It's truly what media would call a cyber-war. It's just astonishing what is happening," Mr Pillay said in Geneva, Switzerland.
In the Netherlands, a 16-year-old boy suspected of being involved in digital attacks by WikiLeaks supporters was arrested.
US attorney general Eric Holder said the Justice Department was looking into cyber attacks on opponents of WikiLeaks and companies that had stopped doing business with it. He spoke at a news conference after a meeting with European Union law enforcement partners on cybersecurity, counter-terrorism and data protection.
WikiLeaks has been under intense pressure since it began publishing around 250,000 secret US diplomatic cables, with attacks on its websites and threats against its founder Julian Assange, who is in custody in Britain fighting extradition to Sweden on sex crime allegations.
US officials say WikiLeaks' actions have thrown diplomacy into disarray, caused countries to curtail dealings with America and, in the case of an earlier release of classified military documents, put the lives of informants at risk.
Many US-based internet companies have cut their ties to WikiLeaks, including MasterCard, Visa, Amazon.com, PayPal and EveryDNS. Those moves have hurt WikiLeaks' ability to accept donations and support publishing efforts - and sparked a bout of web-based warfare.
Retaliatory attacks - which WikiLeaks says it does not sanction - have been claimed by a loose-knit group of "hacktivists" who gather under the handle Anonymous.