The Bush administration was engulfed in angry controversy last night over speculation that a senior White House official had illegally disclosed a CIA agent's identity. 

CNN reported that the Justice Department will investigate former US ambassador to Iraq Joseph C Wilson's allegation that his wife's name Valerie Plame was leaked to columnist Robert Novak 'to retaliate against his criticism of Washington's handling of intelligence on Iraq.'

The White House denied the allegation on Monday. 'The president believes leaking classified information is a very serious matter and it should be pursued to the fullest extent by the appropriate agency and the appropriate agency is the Department of Justice,' White House Press Secretary Scott McClellan told a press conference.

Plame's name was revealed in a July column written by syndicated columnist Novak in the Chicago Sun Times after her husband pooh-poohed Bush's claim in his State of Union address that Iraq had tried to buy uranium in Niger. Embarrassed, Bush backtracked. 

Those 17 words about Iraq, uranium and Niger in Bush's speech have come back again and again to haunt his administration and its claim that it attacked Iraq because Saddam Hussein had accumulated weapons of mass destruction.

After the column appeared the CIA angrily complained that Novak had violated the law by disclosing the identity of an undercover agent, but the US Justice Department's counterespionage section's probe is still in a preliminary stage.

McClellan told reporters that if anyone at the White House had indeed leaked Plame's identity to Novak, s/he should be fired.

'No one was authorized to do this,' he said. 'That is simply not the way this White House operates and if someone leaked classified information it is a very serious matter.'

In an interview with CNN, Wilson described the Bush administration as 'acting like schoolyard bullies, pulling the hair of a little girl.'

CNN reported that Novak -- a contributor to the news network -- refused to divulge his source and denied the leak came from the White House.

'Nobody in the Bush administration called me to leak this,' Novak said. He said he was working on the column when a senior administration official told him the CIA asked Wilson to go to Niger in early 2002 at the suggestion of his wife, whom the source described as 'a CIA employee working on weapons of mass destruction.'

Disclosing a CIA operative's name is a criminal offense in the United States, punishable by up to ten years in jail and $50,000 in fines.