By Matthew Davis BBC News Online

With the US continuing to build a huge attack force in the Gulf, what could Britain contribute to action against Iraq? Military exercises in the Omani desert in 2001 proved without a doubt that Britain has the logistical know-how to rapidly deploy troops and tanks to the Gulf region.

Challenger tank did not work in Oman

Unfortunately the exercises also found that key military equipment - like the Challenger II tank, the SA80 rifle and even troops' boots - failed to cope with an environment pretty similar to much of Iraq.

Critics say the problems highlighted in Operation Saif Sareea II mean Britain could provide little more than token support to US-led action against Saddam Hussein.

The Ministry of Defence says that while no decision has been taken on military action in Iraq, it would make "appropriate modifications" to any equipment needed to operate in a desert environment.

But Britain's experiences in the Gulf War, its role in Kosovo and Afghanistan, coupled with the introduction of new equipment and capabilities mean that it could offer substantial back-up to the US, other defence experts say.

Desert failures

Tank filters clogged Ageing radio system "incapable" AS90 gun filters melted Helicopter parts unserviceable Lynx rotor blades lasted just 27 hours SA80 rifles jammed Shortage of forklift trucks Boots melted or fell apart Source: NAO report

Britain has in service four Tomahawk Cruise missile-carrying submarines which could be used in precision long-range strikes - the Royal Navy's "single biggest difference" since the Gulf War, according to Ian Kemp, of Jane's Defence Weekly.

He said the MoD was bringing into service a batch of roll-on, roll-off transport vessels that would enable quicker deployment of armoured brigades.

The Royal Logistics Corps is currently preparing an operation to test the procedures involved in moving a substantial amount of men and equipment to the military's main port at Marchwood, in Hampshire.

The MoD says this has nothing to do with a possible strike on Iraq. But in its review of Kosovo operations, the MoD identified the importance of Marchwood which "enabled vessels and loads to be prepared in step with political decision-making".

Meanwhile, the MoD has denied reports that two British armoured brigades would be in Kuwait within two weeks.

Experts said it might take at least six weeks for such forces to be in place - working from the moment a decision was taken to send them.

The US would be the major player in military action

While the make-up of such brigades is flexible to an extent, an armoured brigade would include about 4,000 personnel and 1,000 vehicles.

Of these, about 250 would be armoured vehicles and they would include the Warrior infantry fighting vehicle, the Challenger II tank and the AS 90 150mm self propelled gun.

"The big question governing how soon they would actually be used is when the modifications to the Challenger II were done," said Mr Kemp.

The tank would be expected to spearhead any assault by British ground forces, but a National Audit Office report on Oman said dust clogged up the tanks' air filters and they ground to a halt after four hours' service.

"The terrain in southern Iraq is much the same, the desert a little more gritty, the temperature a shade lower - but to all intents and purposes the same problems would be encountered," said Mr Kemp.

The logistical demands of deploying troops are not as great, and soldiers could be in the theatre of conflict within days.

Concerns over "overstretch" related more to peace-time duties and at a time of war Britain could commit tens of thousands of troops, said Mr Kemp.

Harriers could run ground strike missions

Hundreds of British special forces soldiers would be available. They were deployed in the Gulf War - the most infamous example being the ill-fated Bravo Two Zero patrol.

Royal Marine commandos have also had much experience serving alongside US counterparts, most recently in Afghanistan.

Such forces could be deployed from the helicopter-carrier HMS Ocean.

Harrier aircraft would also be used to provide air defence, and the Royal Navy's aircraft carrier-launched Harriers could take on ground attack missions in Iraq.

Advanced missiles

RAF Tornados have, of course been policing the no-fly zones over Iraq for years.

A new anti-aircraft missile which is "almost impossible to evade" could also be deployed by RAF fighter squadrons, it has emerged.

The UK-designed Asraam - Advanced Short Range Air-to-Air Missile - is being fitted to Tornado F3 aircraft after passing a series of vigorous tests, the Ministry of Defence said.

Defence Procurement Minister Lord Bach added: "It can go further and faster than the weapon it replaces - the Sidewinder - and its advanced homing head and in-flight agility mean it will be almost impossible to evade."

Meanwhile, planners at the Permanent Joint Headquarters at Northwood will be refining plans for a variety of military scenarios as the diplomatic crisis unfolds.