Former number two State Department official Richard Armitage says he inadvertently disclosed the identity of CIA employee Valerie Plame in conversations with two reporters in 2003.
Confirming that he was the source of a leak that triggered a federal investigation, the former Deputy Secretary of State said on Thursday that he never intended to reveal Plame's identity.
He apologised for his conversations with syndicated columnist Robert Novak and Washington Post reporter Bob Woodward.
For almost three years, an investigation led by Special Prosecutor Patrick Fitzgerald has tried to determine whether Bush administration officials intentionally revealed Plame's identity as covert operative as a way to punish her husband, former ambassador Joseph Wilson, for criticizing the Bush administration's march to war with Iraq.
"I made a terrible mistake, not maliciously, but I made a terrible mistake," Armitage said in a telephone interview from his home last night.
He said he did not realise Plame's job was covert.
Armitage's admission suggested that the leak did not originate at the White House as retribution for Wilson's comments about the Iraq war.
Wilson, a former ambassador, discounted reports that then-Iraqi leader Saddam Hussein had tried to buy yellowcake uranium from Niger to make a nuclear weapon -- claims that wound up in President George W Bush's 2003 State of the Union address.
Armitage said he was not a part of a conspiracy to reveal Plame's identity and did not know whether one existed.