Visa.com has become the latest victim of a group of activists calling themselves Anonymous who have taken down the site as retaliation for the card company's decision to cut off payments to whistle-blowing outfit WikiLeaks.
At the time of writing, visitors to visa.com are being met with the message: "An error occurred while processing your request."
Earlier a tweet from the group's account (which has since been suspended) stated: "@Anon_Operation: NEXT TARGET: WWW.VISA.COM | TR:30 MINS. GET YOUR WEAPONS ."
The suspected distributed denial of service attack on Visa follows similar moves against MasterCard, PayPal and Swiss bank Postfinance as part of a 'Operation Payback', a campaign against the sites of 'anti WikiLeaks' companies. PayPal.com has also been under concerted attack today.
Channel Four News has been sent a video of a cyber-strike on MasterCard's site, which is now back up after being unavailable for much of yesterday when some SecureCode payments were also affected:
Last night it issued a statement saying: "MasterCard has made significant progress in restoring full-service to its corporate website. Our core processing capabilities have not been compromised and cardholder account data has not been placed at risk. While we have seen limited interruption in some web-based services, cardholders can continue to use their cards for secure transactions globally."
Meanwhile, PayPal has moved to clarify comments made by Osama Bedier yesterday, insisting it did not come under direct pressure from the US government to suspend payments to WikiLeaks.
In a blog, general counsel John Muller says the firm "restricted the account based on our Acceptable Use Policy review" adding: "While the account will remain restricted, PayPal will release all remaining funds in the account to the foundation that was raising funds for WikiLeaks."
This afternoon WikiLeaks moved to distance itself from Anonymous but has not condemned the group's attacks on MasterCard, Visa, PayPal and others.
Says a statement: "WikiLeaks is aware that several government agencies and corporations, including the Swedish prosecutor, Mastercard, PayPal and State.gov have come under cyber-attack in recent days, and have often been driven offline as a result.
The attacks are of a similar nature to those received - and endured - by the Wikileaks website over the past week, since the publication of the first of 250,000 US Embassy Cables.
These denial of service attacks are believed to have originated from an internet gathering known as Anonymous. This group is not affiliated with Wikileaks. There has been no contact between any Wikileaks staffer and anyone at Anonymous. Wikileaks has not received any prior notice of any of Anonymous' actions.
Wikileaks spokesman Kristinn Hrafnsson said: 'We neither condemn nor applaud these attacks. We believe they are a reflection of public opinion on the actions of the targets.'"
Finally, the WikiLeaks saga has also inspired this song: