Hacktivist group Anonymous is claiming to have taken down the Mastercard website in response to the company pulling its services from WikiLeaks.
Making the announcement on the Anon_Operation twitter account, the group said that the Mastercard website had been hit by a Distributed Denial of Service (DDoS) attack as part of Operation: Payback.
Mastercard had cut off payments to WikiLeaks, claiming that the site is engaging in illegal activities.
The credit card firm had said: "MasterCard is taking action to ensure that WikiLeaks can no longer accept MasterCard-branded products."
Anonymous has also claimed to have brought down the site of the Swedish prosecutors office seeking to bring WikiLeaks founder Julian Assange to trial, the BBC reports.
Westminster Magistates’ court yesterday denied Assange bail. He is to be remanded in custody until 14 December, when he will face extradition to Sweden on charges of rape and sexual molestation.