Controversial anti-secrecy website WikiLeaks said Tuesday it was fending off a cyberattack after being lambasted for releasing more supposedly confidential US diplomatic cables.

"WikiLeaks.org is presently under cyberattack," the organization said in a terse message on microblogging service Twitter.

The message provided a link to a cablegatesearch.net website where digital copies of the political documents could be viewed.

The online assault came hours after US officials voiced renewed concern over the risks to individuals after WikiLeaks made public more US diplomatic cables, many of which contained the names of sensitive sources.

State Department spokeswoman Victoria Nuland would not confirm the authenticity of the latest documents, but said "the United States strongly condemns any illegal disclosure of classified information.