An anonymous group of hackers said Wednesday they had launched online attacks to shut down the websites of credit card Mastercard and a Swiss bank that cut off business ties with WikiLeaks.
The self styled "hacktivist" group dubbed Anon_Operation said in one tweet that "www.mastercard.com/ is down" and the site of the credit card giant could not be accessed from Geneva.
The Swiss post office banking service, PostFinance, confirmed Wednesday that its website was suffering denial of service attacks since it closed the bank account of WikiLeaks founder Julian Assange on Monday.
"Since the closure of the account, groups have launched 'Operation Payback' with the aim of blocking PostFinance by simulating hundreds of thousands of connections with the aim of overloading it," said PostFinance.
Attempts to connect to the Postfinance.ch website on Wednesday produced error messages.
"Target: postfinance.ch :: Grab your weapon and its settings: FIRE NOW!" said one tweet on Anon_Operation.
PostFinance closed an account set up by Assange because he gave "false information" on his address, claiming he lived in the Swiss city of Geneva, in violation of banking and money laundering rules.
The bank insists that any deposit belongs to Assange and the money can be transferred where he wishes.
Visa followed its credit card rival in suspending all payments to WikiLeaks, a spokesman for the debit card company said Tuesday.