The former US deputy secretary of state, Richard Armitage, has admitted that he was the person that first disclosed the identity of an undercover CIA agent to the media.
The outing of Valerie Plame in 2003 led to accusations of a smear campaign by the White House against opponents of its Iraq policy.
Ms Plame's husband Joseph Wilson had criticised the Bush administration's plans for Iraq in the run up to the war.
Mr Armitage said he revealed Ms Plame's identity by mistake, as he thought her job was not secret.
