The United States has announced that it is sending tens of thousands of additional military personnel to the Gulf in the biggest deployment yet of its military build-up against Iraq.

Defence Secretary Donald Rumsfeld signed the order to send up to 35,000 reinforcements to the region, including more marines who would spearhead any possible invasion force.

We are going to deploy forces and resources to be prepared US official

The troops are being sent to the Gulf in three amphibious warfare ships.

They will raise the strength of US forces in the region to more than 120,000.

BBC Pentagon correspondent Nick Childs says the US intention is to keep up pressure on Baghdad which, Washington says, has weapons of mass destruction.

"We are going to deploy forces and resources to be prepared," said a senior US official quoted by AFP.

The American deployment comes as the British aircraft carrier Ark Royal set sail for the Gulf in the biggest British naval deployment since the Falklands War.

Captain Massey commands the Ark Royal

The UK Ministry of Defence insists that the role of what will be 8,000 troops in the Gulf has not been decided, but it is clear that it could assist the US in some form of amphibious assault on Iraq.

Captain Alan Massey, commanding officer of the Ark Royal, described the mood among the 1,100 crew on board as a mixture of excitement and nervousness.

"We always hope for the best but plan for the worst," said Captain Massey.

Stance unchanged

The US general who will command any American-led attack, Tommy Franks, has been in Washington this week, briefing his political superiors on his plans.

The US has already sent a hospital ship to the Gulf

Our correspondent says that with the latest deployment, the US military presence in the Gulf is getting close to the minimum size of force analysts believe would be needed to begin an attack.

Although, it is believed that the Pentagon is aiming for a force of a 250,000.

The US is still maintaining that Iraq has weapons of mass destruction, and says that its stance towards Baghdad remains unchanged.

The UN's chief weapons inspector, Hans Blix, has said that so far his teams have not found evidence to back the US claims.

But, he said, Baghdad had yet to answer many questions.

Delayed decision

On Friday, Turkey granted permission for US officials to inspect its ports and airbases, as part of preparations for a possible war.

The surveys are due to start on Monday and are expected to last about 10 days.

Correspondents say Washington has been keen to get Ankara on side in any military operations against Iraq, although the Turkish Government remains sceptical.

The move by Prime Minister Abdullah Gul to allow US teams to inspect Turkish facilities comes a month after Ankara first agreed in principle to the inspections.

The decision has been delayed over a disagreement on the legal status of the US personnel carrying out the surveys.

Any final approval for the stationing of US troops in Turkey in the event of a war against Iraq would have to be endorsed by parliament - where it is likely to face serious opposition.

During the Gulf War of 1991, Turkey's support was critical to the US-led coalition.