Senior White House aide, Lewis Libby, has resigned after being indicted on charges in connection with the leaking of the identity of a CIA operative.
Mr Libby, who is Chief of Staff to Vice President Dick Cheney, is charged with obstruction of justice, perjury and making false statements.
If convicted he could face up to 30 years in prison and a $1.2 million fine.
The identity of CIA agent Valerie Plame was leaked to a US reporter in 2003. Ms Plame's husband, former diplomat Joseph Wilson, had claimed her cover was blown to discredit him after he questioned whether the Bush administration had 'twisted' intelligence in the run up to the war with Iraq.
Revealing the identity of a covert agent is a federal offence. President Bush has accepted Libby's resignation but said everyone is entitled to a fair trial and due process.
Senior presidential adviser Karl Rove has escaped immediate prosecution, but may face further investigations.
