The briefing comes as the US and British military build-up in the Gulf gathers pace.

The first long-range B-1 bombers have left their base in South Dakota, with more to follow. American military headquarters staff are also heading for the Gulf region.

General Franks: Likely commander of US-led operation

There are more than 60,000 US personnel in the region, to be joined shortly by another 25,000.

General Franks is the man expected to spearhead any US-led military operation against Iraq.

UN chief weapons inspector Hans Blix is due to give a more detailed assessment of Iraq's weapons declaration to the UN Security Council on Thursday.

A fuller report, due on 27 January, is seen as a possible trigger for war if Iraq fails to satisfy the inspectors searching for evidence of weapons of mass destruction.

But according to senior UK officials, the UK is urging the US to delay war against Iraq for several months, possibly until autumn, to give the inspectors more time in Iraq, Britain's Daily Telegraph newspaper reports.

Troop deployments

General Franks regularly briefs the president, but is not normally in Washington for several days at a time, as he has been this week, the BBC Pentagon correspondent Nick Childs says.

A senior defence official said the meetings were to give the president an update on deployment activities.

The most significant new additions to the US build-up are the deployment of 1,000 of the general's own battle planning staff and the B-1 bombers.

Our correspondent says a B-1 bomber can carry up to 24 satellite-guided bombs, so each is a potent extra weapon.

More deployments are set to follow.

The outgoing head of the US Marine Corps, General James Jones, told a gathering in Washington that up to 75,000 Marines alone could be deployed.

Inspections continue

The UN weapons teams - now equipped with helicopters to reach sites quickly - checked another eight suspect sites across Iraq on Wednesday.

Tariq Aziz accuses the inspectors of spying

Chemical and biological weapons experts visited four of the sites, including the al-Tareq Public Company in Fallujah, 90 kilometres (55 miles) north-west of Baghdad.

The factory's chief, Saad Hazem, told reporters the site was a chlorine plant.

"This is a civilian production facility. There is no military production here," he said.

The other four sites - including three cement factories in southern Iraq - were visited by nuclear and other experts.

The inspectors were sent back to Iraq in November after the UN Security Council passed a unanimous resolution for Baghdad to show it had disarmed or face possible military action.