By Paul Adams BBC defence correspondent

The American military command with responsibility for the Middle East has announced that it is moving 600 staff from its headquarters in Florida to the Gulf state of Qatar.

The move, in November, will also involve another 400 personnel from subordinate commands, and will test a mobile headquarters.

It is being described as a week-long exercise - somewhat cryptically dubbed "Internal Look" - but in Washington, Pentagon officials have acknowledged that staff members may stay on after it is over.

It seems likely that they will form a planning group for an attack on Iraq.

Central Command does have numerous bases throughout the Gulf, so it is not entirely surprising that exercises should take place in the region.

Command test

Testing a new, rapidly deployable headquarters involving buildings designed for command and control is also one of several recommendations made in a comprehensive review of US defences last year.

	:	US military bases
Click here for map of US regional bases

But this is just the latest in a series of moves that indicate a steady build-up of forces needed for an assault on Iraq.

Cargo vessels have been chartered to carry armoured vehicles to the Gulf.

Equipment for two reinforced armoured brigades, including hundreds of tanks and other vehicles, is already in the region, stored in vast warehouses in Kuwait and Qatar.

The US Air Force, meanwhile, is stockpiling weapons and spare parts. But US officials deny reports that the whole of Central Command is about to be moved to the Gulf in preparation for an attack on Iraq.

With doubts raised over Saudi Arabia's willingness to allow an attack on Iraq to be conducted from its territory, American military planners are focussing more and more on the tiny Gulf state of Qatar.

The air base at al-Udeid has been expanded this year, and now boasts a 15,000 foot (457 metre) runway, capable of accommodating the largest American transport aircraft and bombers.

Satellite pictures

Recent satellite imagery shows, among other things, a new generation of huge reinforced hangars, capable of housing dozens of aircraft.

Central Command has been running Afghanistan operations

Central Command, based at Tampa in Florida, has led the American military involvement in Afghanistan.

It is chief, General Tommy Franks, has been criticised for not moving his headquarters closer to the region, as one of his predecessors, Norman Schwarzkopf, did in the run-up to the 1991 Gulf War.

But political considerations have clearly played a major part in his decision to stay at home.

Base used

After initial suggestions that Saudi Arabia might not allow Washington to use the brand new command and control facility at the Prince Sultan Air Base, outside Riyadh, the base was used to run the air campaign in Afghanistan.

But no planes actually flew from Saudi soil, the kingdom's nervous rulers fearing a possible backlash if they associated themselves too visibly with the war.

This time, Saudi Arabia seems even more adamant. Its possible Washington will be prevented from using the Prince Sultan base at all.

With this concern in mind, the US Air Force began replicating the command and control elements at al-Udeid earlier this year.