Wikileaks website is expected to publish more secret military files.
It is understood Wikileaks is preparing to release as many as 400,000 sensitive intelligence files relating to the US war in Iraq.
The files have been leaked to the website from an unconfirmed source.
The Pentagon is checking its Iraq war databases to prepare for the fallout and has reportedly set up a 120-person taskforce to assess the possible impact.
The ABC reports that if the release goes ahead, it would eclipse the recent publication of more than 70,000 classified US military files on the war in Afghanistan, which caused an outcry in Washington.
The United States has urged Wikileaks to return the new documents to the US military.