Within an hour of his White House speech on Friday, marking the anniversary of the start of the Iraq war, a series of blasts echoed across Baghdad from a suspected mortar or rocket attack on the headquarters of the US-led administration.

US Secretary of State Colin Powell, during a surprise visit to Iraq earlier in the day, also hailed the war, saying it had rid the country of a "horrible dictatorial regime".

But Iraqi journalists gave him a hostile reception, walking out of his news conference in protest at the lack of security in Iraq and the killing of two of their colleagues by US troops in Baghdad on Thursday evening.

The death of a US Marine from wounds suffered in a mortar attack brought to 392 the number of US troops lost in action since the United States and Britain invaded Iraq to rid it of the elusive banned weapons they said Saddam possessed.

Stay the course

Both Bush and Powell urged US allies to stay the course in Iraq after Spain vowed to pull out troops and South Korea refused to take on a combat role.

"Any sign of weakness or retreat simply validates terrorist violence and invites more violence for all nations," Bush told representatives from 83 nations at the White House.

He acknowledged global divisions over the decision to invade Iraq, but said the war had removed a dangerous tyrant.

"There have been disagreements in this matter among old and valued friends," he said. "Those differences belong to the past.

All of us can now agree that the fall of the Iraqi dictator has removed a source of violence, aggression and instability in the Middle East."