Wikileaks activist: 'Anonymous' member, 'Coldblood'
A member of a group attacking Visa and Mastercard's web sites explains why he views the action as "defence of Wikileaks".
Targets of the loose-knit group Anonymous have included Visa, Mastercard and Paypal.
Anonymous member 'Coldblood' has told Jane Wakefield that the group has flooded the sites with data.
Mastercard has acknowledged there had been "a service disruption" involving its SecureCode system, adding: "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."
Entries on the Twitter page of Operation Payback, the Anonymous campaign, said the Visa site had been taken down.
Visa's website was later restored and spokesman Ted Carr said its processing network, which handles cardholder transactions, was working normally.