Hackers have crashed the website of credit card firm MasterCard in apparent retaliation for its blocking of donations to the Wikileaks website, the BBC and other media reported on Wednesday.
MasterCard was not immediately available to comment. The website did not appear to be available online.
Web activists calling themselves Anonymous threatened earlier this week to launch denial of service attacks against businesses such as online payment firm PayPal that had blocked Wikileaks. It is described attempts to censor Wikileaks as part of the first global infowar.
WikiLeaks founder Julian Assange is now in custody in Britain, facing extradition to Sweden for questioning over sex charges, which he denies. Some of his supporters say the charges are politically motivated against him.
(Reporting by Peter Apps; editing by Mark Heinrich)