By Steve Schifferes BBC News Online correspondent in Washington

With war imminent, the US has given the clearest indication yet of how it plans to run a post-Saddam Hussein Iraq.

Maintaining internal order will be the first task

There will be three phases of the US occupation of Iraq, according to the State Department's Undersecretary for Political Affairs, Marc Grossman.

The first stage would be stabilisation, which would focus on finding and destroying weapons of mass destruction, ensuring order and the territorial integrity of Iraq, and protecting the oilfields.

Stages of US Iraq occupation Stabilisation: Military to keep order, guard oilfields Transition: Moves to establish civilian authority Transformation: Iraqi-led interim authority writes new constitution

At that stage Iraq would be run by General Tommy Franks, head of the US central command, and his deputy, retired General Jay Garner, who heads of the Pentagon's office of reconstruction and humanitarian relief.

General Garner would be in charge of ensuring that food and medical supplies reached Iraqis dislocated by the war.

But the US would like to move as quickly as possible to a "transition" phase, where power would gradually be passed to a civilian regime known as the Iraqi Interim Authority.

Creating democracy

That body, made up of prominent Iraqis from both inside and outside the country, would have the job of drafting a new constitution which would respect freedom, democracy and the rule of law.

The Kurds might fight for greater autonomy

Some ministries, including those like health and even oil, could be transferred quickly to civilian control once they had been purged of the top leadership that had been loyal to Saddam Hussein.

But the US military would retain control of external defence and internal security for some time to come.

Mr Grossman made clear that other than the top 12 leaders around Saddam Hussein, the US was prepared to work with "technocrats" within Iraq, as well as military units that surrendered peacefully and did not use weapons of mass destruction.

But he refused to give a timescale for the restoration of civilian rule, saying that it depended on how seriously damaged Iraq was by the war.

International help for reconstruction

In the third phase, "transformation," the Iraqi people would build a viable democracy, using the country's oil wealth to rebuild the country, with Western aid and assistance.

The more UN cover we can get for an operation of this sort, the more international support we can get British official

However, reaching agreement on a new form of government could be difficult, with Kurds and perhaps other ethnic groups pushing for a degree of autonomy that may not be generally acceptable.

Mr Grossman made it clear that the US would not take any long-term decisions about the future of the oil fields, but would only act to get them functioning again.

But he said that the US was not going to be the "banker" to the new Iraqi government, and he said that the US was planning to seek the help of the United Nations, and other bilateral donors, even France and Germany, in paying for reconstruction costs.

"The more UN cover we can get for an operation of this sort, the more international support we can get," said one British official in London, where parallel planning is going on.

Humanitarian row

There is also a short-term problem.

The UN controls the oil-for-food programme, which feeds nearly half the Iraqi population.

And it would need to release funds to any new Iraqi government help pay for fresh supplies.

The US military has stockpiled food for one million refugees, but aid groups say up to four million people could be displaced in the region.

Some aid groups are objecting to working within a military framework as "force enhancers", according to Mary Ellen McNish of the American Friends Service Committee, which represents Quakers.

And the secrecy of the US military has hampered the planning for reconstruction and relief, according to her colleague Jim Matlack.

The aid agencies are also hopeful that the US will move quickly to establish an international civilian administration.

Mr Grossman said that $160m in civilian help was already allocated or in the pipeline, with an additional $36m for voluntary groups.

But aid agencies say that until the government sends the Congress its war appropriations request, it is impossible whether resources will be adequate to meet the scale of the humanitarian crisis to come.

Oil and power

Meanwhile, some Iraqis have suggested that a substantial section of Iraqi's oil revenue should go into a separate Iraqi Bank for Reconstruction and Development, which would oversee reconstruction efforts.

They estimate that between up to half of Iraqi's oil revenues, between $7bn and $15bn a year, could be allocated to these efforts.

And they suggest, to avoid corruption, it should be jointly run by the international community and Iraqi technocrats.

Otherwise, according to Rubar Sandi of the US-Iraq Business Council, control over oil revenues will become the key political battle in the post-Saddam Iraq.