Notes in the hands of a federal prosecutor suggest that Cheney's chief of staff, I. Lewis "Scooter" Libby, first heard of the CIA officer from Cheney himself, The New York Times reported in Tuesday's editions.
A federal prosecutor is investigating whether the officer's identity was improperly disclosed.
The Times said notes of a previously undisclosed June 12, 2003, conversation between Libby and Cheney appear to differ from Libby's grand jury testimony that he first heard of Valerie Plame from journalists.
For the first time, investigators put Cheney in the
"This is a question relating to an ongoing investigation and we're not having any further comment on the investigation while it's ongoing," White House press secretary Scott McClellan said.
Pressed about Cheney's knowledge about the CIA officer, McClellan said: "I think you're prejudging things and speculating and we're not going to prejudge or speculate about things."
McClellan said Cheney — who participated in a morning video conference on the Florida hurricane from Wyoming, where he is speaking at a University of Wyoming dinner tonight — is doing a "great job" as vice president.
The New York Times identified its sources in the story as lawyers involved in the case.
Libby has emerged at the center of Special Counsel Patrick Fitzgerald's criminal investigation in recent weeks because of the Cheney aide's conversations about Plame with Times reporter Judith Miller.
Miller said Libby spoke to her about Plame and her husband, Bush administration critic Joseph Wilson, on three occasions — although not necessarily by name and without indicating he knew she was undercover.
Libby's notes show that Cheney knew Plame worked at the CIA more than a month before her identity was publicly exposed by columnist Robert Novak.
At the time of the Cheney-Libby conversation, Wilson had been referred to — but not by name — in the Times and on the morning of June 12, 2003 on the front page of The Washington Post.
The Times reported that Libby's notes indicate Cheney got his information about Wilson from then-CIA Director George Tenet, but said there was no indication he knew her name.
The notes also contain no suggestion that Cheney or Libby knew at the time of their conversation of Plame's undercover status or that her identity was classified, the paper said.
Disclosing the identify of a covert CIA agent can be a crime, but only if the person who discloses it knows the agent is classified as working undercover.
The Times quoted lawyers involved in the case as saying they had no indication Fitzgerald was considering charging Cheney with a crime.
But the paper said any efforts by Libby to steer investigators away from his conversation with Cheney might be viewed by a prosecutor as attempt to impede the inquiry, which could be a crime.