Mastercard payments may have been affected after its website was hacked earlier today.

The site is one of several targeted by the Anonymous group, hackers opposed to the refusal of the companies concerned to process donations to whistleblower site WikiLeaks.

PayPal and Visa have also come under threat of cyber attack, and hackers may target etail giant Amazon which withdrew site hosting for WikiLeaks. The Mastercard sabotage follows controversy over WikiLeaks’ release of sensitive political information and the arrest of founder Julian Assange after rape allegations.

Mastercard said the attack has not affected payments, and that retailers are still able to process debit and credit cards.

But the BBC has reported some problems with processing payments, saying the authentication service for online payments - called Mastercard SecureCode - has been disrupted.  Payment firm Paypoint has flagged problems with the service, but said it could not tell if retailers were being affected.

PayPoint head of corporate affairs Peter Brooker said, “At the moment we have very little knowledge of the extent to which merchants who use SecureCode are affected. We know that there are some issues.”

Mastercard said in a statement, MasterCard is experiencing heavy traffic on its external corporate website – – but this remains accessible. We are working to restore normal speed of service. There is no impact whatsoever on MasterCard or Maestro cardholders’ ability to use their cards for secure transactions.”