A statement on its website quoted Wikileaks spokesman Kristinn Hrafnsson as saying the attacks were "a reflection of public opinion on the actions of the targets."
The loosely organised campaign to avenge WikiLeaks against those who have obstructed its operations, calling itself Operation Payback, has already temporarily brought down the websites of Visa and MasterCard, and of the Swedish government.
WikiLeaks noted the attacks were similar to those it had received since it began publishing the first of 250,000 U.S. leaked U.S. embassy cables on Nov. 28.
"These denial of service attacks are believed to have originated from an Internet gathering known as Anonymous. This group is not affiliated with Wikileaks. There has been no contact between any Wikileaks staffer and anyone at Anonymous," the statement said.
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"WikiLeaks has not received any prior notice of any of Anonymous' actions."
Some freedom of information campaigners who are sympathetic to WikiLeaks look askance at the Anonymous attacks, saying the website's cause cannot be furthered by denying the freedom of information to others.
A succession of U.S. institutions has withdrawn services from WikiLeaks after the website published thousands of sometimes embarrassing secret US diplomatic reports that have caused strains between Washington and several allies.
