The Defence Department is asking media organisations not to publish or post on websites classified US war files released by the WikiLeaks Web site.

The department has been bracing for a possible leak of as many as many as 400,000 documents from a military database on the Iraq war.

In July, the self-described whistleblower organisation obtained and released nearly 77,000 records on Afghanistan.

The documents are mostly field reports, summarising actions taken by troops and intelligence gathered.

Secretary of Defence Robert Gates has told Congress that the July leak did not expose the most sensitive US intelligence secrets.

But, he also maintained that the release still put US interests at risk because it exposed the names of some Afghans who had cooperated with US forces.