Kelly, the first US journalist to die in the war and the first fatality among 600 journalists "embedded" with coalition forces, was reporting with the US Army's 3rd Infantry Division when the accident happened, the paper said.

"Michael Kelly, the Atlantic Monthly editor-at-large and Washington Post columnist who abandoned the safety of editorial offices to cover the war in Iraq, has been killed in a Humvee accident while traveling with the Army's 3rd Infantry Division," the Post said in an article on its website.

His final column was published by the Post on Thursday.

US President George W. Bush mourned the death.

"The president expresses his sorrow and his condolences to the Kelly family," White House spokesman Ari Fleischer said.

"And the president of course expresses his sorrow and condolences to all of those -- military, civilian, and journalists -- who have died in this combat," Fleischer added.

Kelly is the fifth journalist to die during the conflict, and two others are missing.

Kaveh Golestan, a Pulitzer Prize-winning photographer from Iran, died when he stepped on a landmine in Kifri, in Kurdish-controlled northern Iraq, on Wednesday.

Australian cameraman Paul Moran, on assignment for the Australian Broadcasting Corporation, was killed last month by a suicide bombing in the northern Iraqi town of Khurmal, also under Kurdish control.

Two reporters for the British television network ITN have died, while two others are missing.

Gaby Rado, 48, fell from the roof of the Abu Sanaa hotel in Sulaymaniya, a major town in a Kurdish-controlled area. The circumstances of his death are not known.

ITN correspondent Terry Lloyd is believed to have been killed by US coalition fire near the southern Iraqi city of Basra at the start of the war. Lloyd's French cameraman Fred Nerac and Lebanese interpreter Hussein Osman are still missing.

Kelly was a conservative columnist known for withering criticisms of former president Bill Clinton and his vice president Al Gore, and also worked for the New Republic and Atlantic Monthly magazines.

He was quoted in the New York Times earlier this week as praising the military for allowing journalists to join up with combat units heading for the war zone.

"There was a real sense after the last Gulf War that witness had been lost," he said.

"The people in the military care about that history a great deal, because it is their history. I think that it was the primal motivating impulse here, and they decided to take a gamble."

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