BAGHDAD - Abu Musab al Zarqawi lived for nearly one hour after a US warplane bombed his hideout north of Baghdad and then died of massive internal bleeding, the US military said today citing an autopsy.

In a news conference aimed at countering what he called "misinformation and propaganda", Major General William Caldwell, chief US military spokesman in Iraq, said Zarqawi died as US medics who arrived at the scene were trying to treat him.

US Colonel Stephen Jones, command surgeon for Multinational Forces, said an autopsy conducted by US Defence Department forensic experts concluded that Zarqawi died of massive lung injuries caused by the blasts. He said there was no evidence of beatings or injuries from firearms.

"This was approximately 24 minutes after the coalition forces arrived or approximately 52 minutes after the first air strike on the safe house," Caldwell told the televised conference.

Jones said "all the injuries found were consistent with the types seen in blast victims".

He said Zarqawi slipped in and out of consciousness as he was being treated because his lungs were full of blood. Zarqawi was positively identified by DNA tests conducted by the FBI.

Zarqawi, who as leader of al Qaeda in Iraq was blamed for a campaign of car bombs and beheadings, was killed after a US warplane dropped two 500-pound bombs on his hideout on Thursday. His spiritual adviser was also killed in the strike.

Al Qaeda in Iraq has named a little-known militant, Abu Hamza al-Muhajir, to succeed Zarqawi, according to an internet statement today.

"Blast waves from the two bombs caused tearing, bruising of the lungs and bleeding. This wound was not immediately fatal. Death occurred as lung function deteriorated and the lungs became progressively unable to absorb oxygen," Jones said in a detailed medical report.

Judging by the wounds, Jones said Zarqawi must have been in an enclosed space when the bombs struck.

One of the two doctors who performed the autopsy on Zarqawi and who spoke via telephone from an undisclosed location also said all injuries found on the body were related to blasts.

Fuelling confusion surrounding Zarqawi's death, the US military initially reported that the Jordanian-born militant was already dead when US forces arrived in the bombed-out house in the village of Hibhib.

General George Casey, the top US commander in Iraq, yesterday rejected as "baloney" an account by an Iraqi witness, who said a dying man resembling Zarqawi had been beaten by American troops who arrived at the house. The account was published by an American newspaper.

"The Iraqi people deserve the facts to know that the personal threat of Zarqawi is eliminated and the fact that he was treated better in death that he treated others in life," he told the conference.

Caldwell, who initially reported that only adults had been killed but later confirmed that a young girl was among the six dead, said US forces launched the air strike against the house after concluding it was a "time-sensitive target".

He said the fate of the body would be discussed with Iraq's government.