Bank of America has stopped handling payments for the Wikileaks website, joining several other major financial institutions.
It said it acted because "Wikileaks may be engaged in activities that are... inconsistent with our internal policies for processing payments".
In response, Wikileaks urged its supporters to stop doing business with the bank - one of the world's largest.
MasterCard, PayPal and other companies earlier cut off Wikileaks' payments.
The BBC reports they acted after Wikileaks began publishing thousands of secret US diplomatic cables.
In a statement, Bank of America said it would "not process transactions of any type that we have reason to believe are intended for Wikileaks".
The statement provided no further details.
Wikileaks responded in a message on Twitter, urging "all people who love freedom close out their accounts at Bank of America".
The website also called for businesses to "place your funds somewhere safer".
Wikileaks has recently said it will soon release documents that will point to "unethical" practices" at some US banks.