WikiLeaks says U.S. government has blocked funding

"This is likely to cause a huge backlash against Moneybookers. Craven behaviour in relation to the U.S. government is unlikely to be seen sympathetically," Assange said.

WikiLeaks and Assange have been under fire in recent months from the U.S. government, which increasingly views the site's activities as a threat to national security and soldiers' lives. Assange has been advised to avoid the U.S. for the time being. He also suggested a recent rape investigation of him in Sweden was motivated by animus against WikiLeaks.