The document-sharing site said San Francisco-based CloudFlare, a Web performance and security company, stepped in to help after seeing WikiLeaks' request on Twitter for help to deal with a massive distributed denial-of- service (DDoS) attack, NBC News reported.
An individual or group identifying itself as "AntiLeaks" has taken credit for the attack, which has also caused outages at many WikiLeaks mirror sites.
Hacker group Anonymous, a strong supporter of WikiLeaks, said on one of its blogs: "We are now witnessing cyberwars, with most Wikileaks sites under sustained DDoS attack over several days. On one side are WikiLeaks itself and its hactivist (sic) supporters, such as Anonymous. On the other side are U.S. Govt. supporters."
Anonymous has been responsible for many of the DDoS attacks on government Web sites in the past, including the CIA.
In a posting Monday, AntiLeaks said Internet speculation that the group is U.S.-government backed is not true.
"We find the speculation that we are not behind these attacks and/or that we are CIA/NSA/FBI or even WikiLeaks themselves to be downright comical," it posted.