MasterCard said on Wednesday that its main website was offline for a short period of time due to a weather-related issue at a third-party ISP and not a distributed denial-of-service (DDOS) attack as claimed by WikiLeaks.

WikiLeaks wrote on Twitter on Tuesday that "hacktivists" had taken down MasterCard "over the continuing WikiLeaks fiscal embargo." An anonymous Twitter user, "ibombhacktivistm," wrote that MasterCard.com had been taken down.

A MasterCard spokesman said that the "cause was not a hack."

MasterCard's main website came under attack last year by Anonymous. The distributed collective of hackers also conducted DDOS attacks against the websites of PayPal, Visa, and the Swiss Bank PostFinance after those companies stopped processing payments for WikiLeaks when it began releasing portions of 250,000 secret U.S. diplomatic cables in November 2010.

The outage of MasterCard.com on Tuesday was sudden and abrupt, which is not a common pattern for how DDOS attacks progress, said Paul Mutton, a security analyst with Netcraft, on Wednesday.

"Most DDOS attacks we witness also result in longer response times during at least some part of the attack, which we did not see during the MasterCard outage," Mutton said. "It was either responding quickly, or not at all."

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