Thousands of confidential US State Department documents have been released by the whistle-blowing website WikiLeaks.
The explosive revelations contained in 250,000 diplomatic cables are threatening to start a global diplomatic crisis.
The leak of the material has been strongly condemned by the US and British governments.
The Guardian is one of five newspapers to have had access to the cables, along with the New York Times, Der Spiegel in Germany, Le Monde in France and El Pais in Spain.
The Guardian said that the newspapers which had seen the leaks planned to publish extracts from the most significant cables but did not intend to "dump" the entire database into the public domain or to publish names that would endanger innocent individuals.
The White House said that the disclosure of confidential diplomatic communications on the front pages of newspapers around the world would "deeply impact" US foreign interests.
"To be clear - such disclosures put at risk our diplomats, intelligence professionals, and people around the world who come to the United States for assistance in promoting democracy and open government," said White House press secretary Robert Gibbs.
He added: "By releasing stolen and classified documents, WikiLeaks has put at risk not only the cause of human rights but also the lives and work of these individuals."
The Foreign Office said: "We condemn any unauthorised release of this classified information, just as we condemn leaks of classified material in the UK".
"They can damage national security, are not in the national interest and, as the US have said, may put lives at risk. We have a very strong relationship with the US Government. That will continue."