Mr Rove (right) is President Bush's chief political strategist

A federal prosecutor is investigating whether any officials broke the law by revealing the name of a covert agent.

A Time magazine reporter said top presidential aide Karl Rove had been the first to hint at the identity.

Correspondents say Mr Bush's mention of crimes is a shift from his pledge to fire anyone involved in the leak.

CIA agent Valerie Plame is married to former US diplomat Joseph Wilson, who accused the Bush administration of distorting intelligence on Iraq.

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

Profile: Karl Rove

Mr Rove has denied being behind the leaking of her identity to the media.

At the weekend, Time journalist Matthew Cooper wrote that Mr Rove did not disclose Ms Plame's name, but did say that the wife of a government critic worked for the CIA.

Mr Cooper also wrote in Time that he discussed Mr Wilson and his wife with Lewis Libby, a senior aide to Vice-President Dick Cheney.

Mr Bush told reporters he did not know all the facts and urged them to wait until the inquiry was complete before "you jump to conclusions".

"I would like this to end as quickly as possible so we know the facts, and if someone committed a crime they will no longer work in my administration," he said at a news conference.

The BBC's Oliver Conway in Washington says Mr Bush's statement appears to leave him some room for manoeuvre.

The evidence made public so far does not conclusively show a crime has been committed, he says.

The Democratic Party accused Mr Bush of lowering the "ethics bar".

Smear allegations

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 wrote an opinion piece for the New York Times in which he accused Mr 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 later 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.