Security at the base has been stepped up in recent weeks

The move to deploy Armed Response Vehicles (ARV) with "overtly" armed officers is aimed at "protecting life and preventing acts of terrorism and sabotage at or near the base," say Gloucestershire Police.

The ARVs will be supporting other officers and undertaking road checks under the provision of the Terrorism Act 2000.

Acting Deputy Chief Constable Martin Baker said: "As a result of the current security situation, we are taking the necessary steps to deter and disrupt serious criminal activity.

Protesters have targeted the base

"We are also providing a capability to respond immediately to any incident requiring the deployment of trained firearms officers.

"We are seeking to minimise the inconvenience to the communities affected and are grateful to local residents for the co-operation we are receiving at this time," he added.

The Ministry of Defence said it could not comment on security measures inside the base.

A spokesman told BBC News Online: "We are under instruction not to comment at the present time."

'Deadly force'

Security in the area has been stepped up since 14 US B-52 bombers arrived just over two weeks ago.

Police increased patrols and invoked special stop and search powers to detain anyone regarded as suspicious within a mile of the perimeter fence.

On Wednesday, signs were attached to the perimeter fence which warned: "Use of deadly force authorised".

A spokesman for Gloucestershire police said he was unable to confirm how many ARVs and other officers were currently being used as it was not policy to comment on such issues.

Wiltshire and Gloucestershire county councils have been asked for permission to close some roads in the area. No nearby residents will be moved from their homes.

Arrests made

RAF Fairford is designated by Nato as a forward base for US warplanes, and was last used by the bombers during the 1991 Gulf War and 1999 Kosovo conflict.

A large-scale peace protest is set to take place there on Saturday.

The base, which is about six hours flying time from Iraq, has become the focus of a series of anti-war protests by people from all over the country.

A number of campaigners have been arrested and charged after breaking in by cutting through the perimeter fences.