JOIN USThe credit-card company had previously blocked donations via MasterCard to WikiLeaks, following the example of rival Visa and the online payment service PayPal. MasterCard's website could not be accessed Wednesday afternoon.
The attackers claimed over their Twitter account responsibility for the denial-of-service attack and said it was part of "Operation:Payback". Datacell, the Iceland-based commercial arm of WikiLeaks, said it would taken legal action against both credit-card companies.
The personal account of WikiLeaks chief Julian Assange, 39, at a Swiss bank was closed earlier this week. Assange is in Wandsworth Prison in London after Sweden sought his extradition on forced sex charges. Sweden denies this has any connection with US efforts to bring Assange to justice for gradually releasing 250,000 leaked US diplomatic cables.
Assange has denied the Swedish allegations, saying they are part of a smear campaign. A German foundation which has been a conduit for donations to WikiLeaks, the Wau Holland Stiftung, said its lawyer was sending a warning to PayPal, charging that about 10,000 euros ($13,000) had been frozen by PayPal, a subsidiary of eBay.
It said this was the amount donated via PayPal from Friday to Saturday, when the PayPal account was finally frozen. It said PayPal's allegation of "illegal activity" was libellous and must be deleted from the PayPal blog.
The only remaining donation channels mentioned Wednesday on the WikiLeaks website were remittances to Wau Holland's bank account in Germany, transfers to a bank account in Iceland or mailing cash or cheques to a post-office box in Melbourne, Australia.
Supporters of Assange were believed to have targeted the website of the Swedish prosecution agency overnight Wednesday, blocking access to the agency's site. The website was back up Wednesday but users could experience some disturbances, the Prosecution Authority said.
Another target was a website operated by a Swedish lawyer, who represents the two women who filed the complaints against Assange. Australia pledged consular help to Assange and backed away from its claim that releasing confidential US diplomatic cables had constituted a crime.