Gangs kept up their looting spree on Saturday in Iraq's main cities as American and British forces turned their guns on Tikrit, Saddam Hussein's home base and the last important town still to fall.

Humanitarian agencies appealed to the United States to help check the lawlessness that threatens to delay badly needed aid, and American officials hurriedly made plans for a conference early next week to discuss the country's future government.

In Baghdad, this correspondent heard sporadic gunfights among Iraqis through the night into Saturday. The fighting was mainly concentrated in Saddam City, a sprawling slum in northeast Baghdad and home to many Shi'ites.

US forces, who swept into this city of five million three days ago and helped topple statues of Saddam, did not intervene.

US troops headed into the northern city of Mosul, Iraq's third largest, in the first major deployment there since Saddam's forces surrendered without a fight on Friday.

The fate of Saddam remained a mystery.

Citing communications overheard from Iraqis, one US official told Reuters: "I'd say it's leaning slightly more to dead than alive." But the officials said the 'chatter' did not add up to conclusive proof.

Visiting US servicemen wounded in the war, President George W Bush said: "I don't know if [Saddam] is dead or alive. I do know he is no longer in power."

Iraq's UN ambassador, Mohammed Aldouri, the first Iraqi official to concede the fall of the regime, left the US for Syria, saying he did not want to represent his country under a US-British occupation.

"When this occupation ends... I will be the first to enter my country as a free country," Aldouri said.

Naked Greed

US bombers pounded the positions of Saddam loyalists in Tikrit, 180km north of Baghdad. US troops also tightened their grip over Mosul and the oil hub of Kirkuk, both seized with the help of Kurdish peshmerga fighters.

Kirkuk was quiet overnight. But in Mosul, as in Baghdad and the southern city of Basra, crowds stripped and torched buildings in a frenzy of arson and plunder.

"The breakdown in law and order will delay the arrival of humanitarian assistance from the outside because the security conditions are not there," David Wimhurst, spokesman for the United Nations Office of the Humanitarian Coordinator for Iraq, told Reuters in Amman, Jordan.

He said US military planners had failed to foresee the collapse of law and order after Saddam's fall.

The International Committee of the Red Cross said Baghdad's medical system had all but collapsed due to combat damage and looting. Few medical or hospital support staff were reporting for work and many patients had fled.

US Defence Secretary Donald Rumsfeld denied Iraq was falling into chaos, saying television images of isolated acts of looting and violence were being played 'over and over again' for sensational effect.

Plotting Iraq's Future

The US hopes to bring together a wide variety of Iraqis next week to decide who will initially govern a country divided among the majority Shi'ites, the minority Sunni Muslims who have long ruled and separatist Kurds in the north.

"We expect this to be the first in a series of regional meetings that will provide a forum for Iraqis to discuss their vision of the future and their ideas regarding the Iraqi interim authority," said State Department spokesman Richard Boucher of the gathering in Nasiriya in southern Iraq.

Asked when an interim authority might emerge, he said: "We are hopeful that it will be a matter of weeks."

UN special envoy Rafeeuddin Ahmed was invited to meet on Monday with officials from the State Department, White House National Security Council and Defence Department for talks on the post-conflict period, said UN spokesman Fred Eckhard.

No UN officials were invited to the Nasiriya meeting.

In the Russian city of St Petersburg, the leaders of France, Germany and Russia -- strong opponents of the US-led war now in its 24th day -- reaffirmed their belief that the UN must play the key role in rebuilding Iraq.

Finance ministers from the Group of Seven industrialised nations met in Washington to discuss how to rebuild oil-rich Iraq's economy, shattered by war and economic sanctions.

US soldiers began spreading through the oil fields near Kirkuk, which provide 40 per cent of Iraq's oil revenue.

The Kurds' promised withdrawal from Kirkuk, their traditional capital, was designed to calm fears in Ankara that they could use the city's wealth to finance an independent state and thereby feed separatism among Turkey's own Kurdish minority.