By Toby Shepheard
FAIRFORD, England, Sept 28 (Reuters) - Five suspects arrested by British police on suspicion of terrorism and explosives offenses after white vans drove towards an airbase used by US forces were all British nationals from London in their early 20s, police said on Monday.
British officials said they were still investigating any possible motive for the incident near RAF Fairford, a British base that houses US bombers which fly missions against Iran.
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.
Britain's Sky News cited a statement from the Iranian embassy denying involvement in the incident.
Officers seized the men in the early hours of Sunday after a tip-off from a local farmer that three large white vans were heading to the military airfield in western England. Iran's Revolutionary Guards have said the base was a legitimate target.
Police said in a statement on Monday they had multiple new lines of inquiry after they examined the scene overnight. Counterterrorism officers were interviewing the five men, all aged between 23 and 25.
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".
Trump said the suspects had been under investigation by British and US authorities, but there was doubt raised 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 the police after seeing a group of "hooded and masked men" running into the fields, told BBC radio she believed that it was only her phone call to the 999 emergency hotline that "foiled whatever plans they had".
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 noted 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."
TERRORISM THREAT SEVERE
Britain in April raised its national terrorism threat level to "severe" from "substantial" after a series of antisemitic incidents in north London, indicating a terrorist attack within six months is considered highly likely.
Police said they were investigating Iran links to many of the incidents in which properties connected to the Jewish community or Iranian dissidents were targeted.
In May, Britain imposed sanctions on 12 individuals and entities linked to Iran, accusing them of involvement in hostile activity including plotting attacks and providing financial services to groups seeking to destabilise the UK and other countries. Iran has repeatedly denied involvement in attacks or plots in the UK and elsewhere.
Responding to the Fairford arrests, the US Embassy issued a security alert saying US citizens should "exercise caution" and be "mindful of personal security".
"US-associated facilities, gatherings, and organisations may be at heightened risk," the statement said. Security was also stepped up at other US air bases in Britain.
The British government had given authorisation to the US to use bombers based at Fairford to strike Iranian missile sites that were attacking ships in the Strait of Hormuz.
The government has said Prime Minister Andy Burnham is being regularly updated on the incident and he dropped out of several events at his Labour Party's annual conference on Sunday.
Iran's Revolutionary Guards had warned Britain in July not to allow US bombers to fly from Fairford, saying any base used to launch attacks would be a legitimate target.
In Fairford, police have imposed a 400-metre cordon around the base and evacuated residents from 85 homes.
A bomb disposal robot could be seen on Sunday operating around the three white vans, while security was stepped up around the base. Armed police stood guard at the main entrance while large machinery was used to block 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)
