British counter-terrorism police were on Sunday probing a “major” incident near a base used by the US air force after arresting five men on suspicion of “preparing a terrorist act”, police said.

In March, then prime minister Keir Starmer granted permission for “defensive” US action against Iranian missile sites from two UK bases including Fairford.

Armed officers detained the group in the early hours of Sunday after a call to emergency services about three “suspicious vehicles which appeared to be travelling towards the airbase”, London’s Metropolitan Police said in a statement.

The suspects were initially held near the Royal Air Force (RAF) Fairford air base in Gloucestershire, southwest England, on suspicion of explosives offences.

Some 85 households in the nearby village of Whelford were advised to evacuate and army bomb disposal experts were called in to examine three vans stopped on a rural road.

“Counter Terrorism Policing can now confirm they are leading an investigation into an incident which took place overnight near RAF Fairford in Gloucestershire,” the Met statement added.

Broadcast aerial footage showed a bomb disposal robot on a rural road moving around the vans, two of which had their rear doors open.

Police believed the incident had been “contained” and a 400-metre cordon had been put in place. Armed officers could be seen guarding the entrance to the base.

Prime Minister Andy Burnham was being kept updated on the incident, a government spokesperson said.

“We are grateful to the emergency services, who have acted quickly to detain several suspects and put measures in place to keep the community safe,” the spokesperson said.

“It would be inappropriate to comment further whilst investigations are ongoing.”

Defence Minister Wes Streeting thanked “emergency and specialist teams” deployed to the scene.

“We can be reassured that this is being dealt with,” he said on X.

Gloucestershire Police said earlier it had declared a “major incident” with several men arrested “on suspicion of offences under the Explosives Act”.

Villagers evacuated

Residents were evacuated to a nearby leisure centre, police said.

Villager Julian Tudsbery said he was woken and advised to leave at about 7am (11am PKT) by police “banging on the door”.

He said a fellow villager had alerted police in the middle of the night after spotting the vans.

“They phoned the airbase police, who didn’t answer the phone. It just rang out so she dialled 999,” he told the BBC.

Fairford is the UK base of the 501st Combat Support Wing, a US air force administrative support wing, which said in a statement that no US air force personnel had been involved in the incident.

“The 501st Combat Support Wing appreciates the swift response and continued support of our local law enforcement partners,” it said.

“We remain in close coordination with our UK partners to help ensure the safety and security of both our military and local communities,” it added.

The MP for the area, Roz Savage, described the situation as “worrying”.

“I have contacted the police for further updates and I’ve been told that it is believed the incident is contained,” she said on X.

The incident comes amid concerns about the actions of hostile foreign states.

Interior Minister Shabana Mahmood has accused Iran and Russia of using proxies to carry out criminal activities on their behalf on UK territory.

Earlier this month, reports said British military sites had been targeted by drones more than 300 times over the past year.

Britain’s defence ministry did not disclose who was behind the drone activity, but the figures come as European countries have warned of an increase in suspected Russian hybrid operations on their territory. Russia denies mounting hybrid attacks on Western nations.

Britain said in July its armed forces were ready to protect the country from any attack after Iran’s Revolutionary Guards issued a warning not to allow US bombers to fly from Fairford.