WASHINGTON — A State Department memo that has caught the attention of prosecutors describes a CIA officer's role in sending her husband to Africa and disputes administration claims that Iraq was shopping for uranium, but does not identify her by name or say she worked undercover, a retired department official said yesterday.

The classified memo was sent to Air Force One just after former Ambassador Joseph Wilson went public with his assertions that the Bush administration overstated the evidence that Iraq was interested in obtaining uranium from Niger for nuclear weapons.

The memo has become a key piece of evidence in the CIA leak investigation because it could have been the way someone in the White House learned — and then leaked — the information that Wilson's wife, Valerie Plame, worked for the CIA and played a role in sending him on the mission.

The document was prepared in June 2003 at the direction of Carl Ford Jr., then head of the State Department's bureau of intelligence and research, for Undersecretary of State Marc Grossman, said the retired official, who requested anonymity because the investigation is still under way.

The former official said the memo focused on Wilson's trip and the State Department's disagreement with the White House's claim that Iraq was trying to purchase yellowcake uranium from Niger. He said the fact that the CIA officer and Wilson were married was largely an incidental reference.

Deputy Secretary of State Richard Armitage called Ford after Wilson's op-ed piece in The New York Times and his TV appearance on July 6, 2003, in which he said the White House had twisted intelligence on Iraq. Armitage asked that the memo be sent to Powell, who was traveling to Africa with President Bush, the former official said.

The memo said Wilson's wife worked for the CIA and suggested her husband go to Niger because he had contacts there and had served as a diplomat in Africa. However, the official said the memo did not say she worked undercover for the intelligence agency, nor did it identify her as Valerie Plame.

Her identity was disclosed first by columnist Robert Novak. The leak investigation by special counsel Patrick Fitzgerald is looking into who in the Bush administration leaked Plame's identity to reporters and whether any laws were broken. Wilson believes the White House leaked the name as retribution for his criticism.

Bush said Monday he would fire any member of his staff who "committed a crime," a change from his previous vow to fire anyone involved in the leak.

The past two weeks have brought revelations that White House aides Karl Rove and I. Lewis "Scooter" Libby discussed Plame with reporters before her name was revealed to the public.