A US journalist says presidential aide Karl Rove was the first to tell him that the wife of a prominent administration critic was a CIA agent.
Mr Rove, right, is President Bush's chief political strategist
Time magazine reporter Matthew Cooper said Mr Rove did not disclose Valerie Plame's name, but said the wife of a government critic worked for the CIA.
Mr Rove has denied being behind the leaking of her identity to the media.
A federal prosecutor is investigating whether any officials broke the law by revealing the name of a covert agent.
Newspaper columnist Robert Novak first publicly revealed that Ms Plame was a covert CIA agent in July 2003, citing two administration officials.
That was shortly after her husband, Joseph Wilson, wrote an opinion piece for the New York Times in which he accused President George W Bush's administration of twisting intelligence on Iraq.
Mr Wilson says he travelled to Niger to investigate a claim that Iraq had tried to buy nuclear material there, but found no evidence to prove it.
President Bush used the Niger claim as part of the justification for the 2003 invasion.
Novak wrote that an official had told him the trip was inspired by Ms Plame.
Mr Wilson alleges that his wife's name was deliberately leaked in a bid to undermine him.
Writing in the current issue of Time after testifying in court last week, Cooper said: "So did Rove leak Plame's name to me, or tell me she was covert? No.
PLAME AFFAIR TIMELINE
Feb 2002: Joseph Wilson looks into reports that Iraq tried to buy uranium in Niger
6 July 2003: Mr Wilson goes public about investigation
14 July 2003: Columnist Robert Novak writes the trip was inspired by Ms Plame - Matthew Cooper reports that he had similar information
30 September: Justice department launches probe
24 June 2004: President Bush testifies in case
15 July: Cooper and Judith Miller ordered to testify about sources
10 August: Miller and Cooper sentenced for contempt of court
28 June 2005: Supreme Court refuses to hear appeal
6 July: Miller jailed after appeals fail, Cooper agrees to testify
"Was it through my conversation with Rove that I learned for the first time that Wilson's wife worked at the CIA and may have been responsible for sending him? Yes. Did Rove say that she worked at the 'agency' on 'WMD'? Yes."
This week, Newsweek magazine quoted Mr Rove's lawyer as saying his client did discuss Ms Plame with Cooper in an e-mail, but did not mention her name.
Cooper also wrote in Time that he discussed Mr Wilson and his wife with Lewis Libby, a senior aide to Vice-President Dick Cheney.
The journalist said he asked Mr Libby whether he had heard anything about Mr Wilson's wife sending her husband to Niger, and Mr Libby replied: "Yeah, I've heard that too."