Hackers have declared an Internet war in support of WikiLeaks, with groups of anonymous attackers disabling major credit card websites in retaliation for denying service to the controversial website.
The group, going by the name "Anonymous," rallied its supporters in a Twitter post Wednesday, calling for them to get their "weapons" ready to attack the Visa website for the next phase of "Operation Payback."
The same group claimed responsiblity for crippling the MasterCard website for much of the day Wednesday using denial of service attacks, which overwhlem a website with data requests.
Both Visa and MasterCard have stopped processing donations to WikiLeaks as the online organization faces tremendous political pressure for publishing secret U.S. diplomatic cables.
Wikileaks released a cable Wednesday showing that in February 2010 U.S. officials lobbied Russia on behalf of MasterCard and Visa to ensure that a proposed Russian law did not adversely affect their businesses.
There are now more than 1,000 Internet "mirror sites" hosting WikiLeaks content, which is more than double the number of sites that existed days ago.
An executive of the online payment company PayPal said Wednesday it decided to suspend its business with WikiLeaks after the U.S. State Department said the website's activities are illegal.
State Department spokesman P.J. Crowley said in a Twitter message that the U.S. government did not write to PayPal requesting any action regarding WikiLeaks.
The website's founder, Julian Assange, surrendered to authorities in Britain Tuesday and is in custody while he fights extradition to Sweden, where he is wanted for questioning about alleged sex offenses.
Swedish prosecutor Marianne Ny says the investigation has nothing to do with WikiLeaks and that she has no intention of handing Assange over to the United States if he is extradited to Sweden.