Bank of America refuses all WikiLeaks transactions

"Bank of America joins in the actions previously announced by MasterCard, PayPal, Visa Europe and others and will not process transactions of any type that we have reason to believe are intended for WikiLeaks," the largest US bank said in a statement.

"This decision is based upon our reasonable belief that WikiLeaks may be engaged in activities that are, among other things, inconsistent with our internal policies for processing payments."

Bank of America spokesman Scott Silvestri declined to comment beyond the official statement.

The action comes weeks after WikiLeaks founder Julian Assange claimed in an interview with Forbes magazine that a "megaleak" by the website will target a major US bank "early next year."

He has previously said that he has a treasure trove of documents on Bank of America, whose shares tumbled more than three percent on November 30 shortly after the Forbes interview was released.

Assange on Saturday denounced a "new type of business McCarthyism" in the United States after the BOA decision, telling AFP the move was aimed at trying to "deprive this organization the funds that it needs to survive."

The action is the latest blow against the website, which has been exposing classified US diplomatic cables that reveal embarrassing assessments of world leaders and provide a rare glimpse into the work of scores of US embassies.

The United States has angrily criticized the release of the documents, saying it endangers national security, and the US Attorney General has launched a criminal investigation into the site.

But Assange has won the support of a collection of anonymous "hacktivists" -- computer hackers who in the name of free speech have targeted institutions that refuse to deal with the website.

On Saturday they released a statement calling for a boycott of BOA.

"We ask that all people who love freedom close out their accounts at Bank of America," the group known as "Anonymous" said on its blog AnonOps Communications.

After taking down the websites of Visa, Mastercard and others with cyber attacks -- part of what they call "Operation Payback" -- the loose-knit group tried but failed on Thursday to knock retail giant Amazon.com offline.