By Toby Shepheard
FAIRFORD, England, Sept 28 (Reuters) - Iran denied involvement on Monday in a suspected plot to attack a British airbase used by the United States to strike Iranian sites, and police said five men arrested over explosives and terrorism offences were British nationals.
British police arrested the five early on Sunday after being alerted to three white vans driving towards RAF Fairford, a British base that houses US bombers that fly missions against Iran.
Iran's Revolutionary Guards
said in July the base was a legitimate target.
Police said on Monday the five detained men were British nationals from London in their early 20s, and that they were trying to understand a motive.
A source familiar with the investigation said an Iranian-linked motive was considered the most likely although a Russian sabotage operation or an Islamist plot were also being looked at as possibilities.
Iran's embassy in London said in a statement it "categorically rejects and strongly condemns the recent unfounded and malicious speculations", which it said would fuel "Iranophobia propaganda" in Britain.
MULTIPLE LINES OF INQUIRY
Police said they had multiple new lines of inquiry after examining the scene overnight.
Counter Terrorism Policing Senior National Coordinator Vicki Evans said she was aware of speculation about the motive and geopolitical questions that were being raised, but asked that police be given "the space to work carefully and clearly".
US President Donald Trump said on Sunday the suspects had been looking to do "big damage" and had been under investigation by British and US authorities, but doubts were voiced in British media about the degree to which they had been under surveillance, given how close they had come to the base.
The source familiar with the investigation said the arrests were not "intelligence-led" although security had been heightened at the base, suggesting authorities were aware of an increased threat.
The farmer, who alerted police after seeing a group of "hooded and masked men" running into fields, told reporters she believed it was her phone call to the 999 emergency hotline that foiled any plot.
Defence minister Wes Streeting told the BBC the farmer, who has not been identified, had only a "partial picture" of the investigation, without providing further clarification.
He said he would not speculate about motives during a live investigation, but that Britain faced a general threat from Iran.
"We know that Iran and their proxies wish to do us harm. We know that they hate our democracy, and we know that we regularly have to thwart Iranian attempts to threaten either our interests or indeed our allies," he said.
TERRORISM THREAT SEVERE
Britain raised its national terrorism threat level to "severe" from "substantial" in April after a series of antisemitic incidents in north London. This level indicates a terrorist attack within six months is considered highly likely.
Police said they were investigating links with Iran to many of the incidents in which properties connected to the Jewish community or Iranian dissidents were targeted.
Britain imposed sanctions on 12 individuals and entities linked to Iran in May, accusing them of involvement in hostile activity including plotting attacks and providing financial services to groups seeking to destabilise Britain and other countries. Iran has denied involvement in attacks or plots in Britain and elsewhere.
After the Fairford arrests, the US Embassy issued a security alert saying US citizens should "exercise caution" and be "mindful of personal security". Security was stepped up at other US airbases in Britain.
The British government had given authorisation to the US to use bombers based at Fairford to strike Iranian missile sites attacking ships in the Strait of Hormuz.
The government has said Prime Minister Andy Burnham is being regularly updated on the incident. He dropped out of several events at his Labour Party's annual conference on Sunday.
In Fairford, police have imposed a 400-metre cordon around the base and evacuated residents from 85 homes.
A bomb disposal robot was on Sunday operating around the three white vans, and security was stepped up around the base. Armed police stood guard at the main entrance and large machinery blocked other access points.
An image on social media purported to show some of the suspects, seated shirtless with hands behind their backs, after their arrest. Reuters was unable to independently locate and verify the source of the photograph.
(Additional reporting by Sarah Young and Sam Tabahriti; Writing by Kate Holton and Michael Holden; Editing by Peter Graff, Andrew Cawthorne, Alexandra Hudson)
