Al-Qaeda may have plans to attack British warships in the Gulf, according to the Royal Navy's commander in the region.
The Gulf deployment is the navy's biggest since the Falklands war
Rear Admiral David Snelson said information provided by captured al-Qaeda suspects made it clear suicide bombers in high-powered speedboats packed with
explosives could be sent to ram the vessels.
He said this was the biggest threat facing his forces.
Admiral Snelson said the danger would instantly increase the moment war with Iraq began.
More than 130 warships and auxiliary vessels are now crowded into the Gulf.
Most are American, but about 30 are British.
We know al-Qaeda are active within this region
Rear Admiral David Snelson
It is the Royal Navy's biggest deployment since the Falklands conflict in 1982.
Admiral Snelson said warning shots had already been fired at small boats approaching the ships at high speed.
He said: "We know al-Qaeda are active within this region.
"There are a lot of small high speed boats operating in the region, and it is one of the challenges to know whether they are smugglers, a fishing boat, or a high speed boat with hostile intent."
Al-Qaeda was blamed for an attack on USS Cole in October 2000 which killed 17 American sailors and another last year which killed Bulgarian crewman on board the French merchant ship Limburg.
In both cases militants approached warships in tiny boats and detonated explosives.
Admiral Snelson said the security of British ships was being boosted by seals trained by US naval marine biologists to seek out terrorist frogmen carrying limpet mines.
"They're very good at detecting underwater movement," he said.
British naval forces, armed with machine guns and night vision goggles, are also patrolling in small vessels and helicopters, watching out for sneak attacks.
The Ministry of Defence has set up an electronic bulletin board to allow members of the public to send goodwill messages to the Armed Forces in the Gulf.
It was set up because of the amount of post generate by goodwill letters and parcels.
Messages are free and can be sent to the Navy (including Royal Marines), RAF or Army.
The board can be accessed at the BFPO's website.