Hackers claimed Wednesday to have taken down MasterCard's website in retaliation for the company's decision to cut off services to WikiLeaks. "WE ARE GLAD TO TELL YOU THAT http://www.mastercard.com/ is DOWN AND IT'S CONFIRMED!," anti-censorship group Anonymous said in a post to its Twitter site for an initiative it has dubbed Operation Payback. Attempts to load the MasterCard site Wednesday morning were unsuccessful. A spokesman for the company told msnbc.com that the it did not have any information or comment at this stage. The group has also claimed responsibility for distributed denial-of-service (DDoS) attacks on the website of the Swedish prosecutor's office that is seeking WikiLeaks founder Julian Assange for alleged sex crimes, PayPal and the Swiss bank that froze Assange's assets, the BBC reported. The office of the lawyer representing Assange's two accusers in Sweden also told NBC News Wednesday that its website was inaccessible due to hacker attacks. WikiLeaks tweeted a statement on Wednesday addressing Assange's arrest and noting efforts to cut off the flow of money to WikiLeaks.