Downing Street warned over new WikiLeaks files

David Cameron has been warned that fresh revelations from whistle-blowing website WikiLeaks about US foreign policy could expose Britain's secret relations with its main ally.

The Prime Minister's office has been contacted by the US Ambassador in London, Louis Susman, in advance of the third set of disclosures.

WikiLeaks announced earlier this week that it planned to publish three million classified files, many of which are believed to have come from the US State Department.

This could shed light on previously unknown links with allies and their involvement in the Iraq and Afghanistan wars as well as embarrassing criticism of the leaders of Afghanistan, Pakistan and Russia.

The US government warned that the revelations would be harmful to national security. State department spokesman Philip Crowley said: "It does put lives at risk."

In July WikiLeaks published the Afghan War Diaries which detailed the deaths of 20,000 people. This was followed last month with 391,832 classified US files on the Iraq war.