British police investigating a suspected plot involving an air base used by the US to target Iran said they had arrested a dual UK-Iranian national on Thursday on suspicion of preparing terrorist acts.
In an incident which triggered a huge police response, raised alarm among Western allies, and remains largely unexplained, five British men in their 20s were arrested on Sunday on suspected terrorism and explosive offenses near RAF Fairford in western England.
The men were later released without charge on police bail. But counter-terrorism police said they were considering whether a foreign state was involved in the incident, and Prime Minister Andy Burnham said on Wednesday it might have had Iranian involvement.
Investigation into Fairford incident is 'hugely complex'
Police said they had arrested the 27-year-old dual national in London while a second British man, 26, had also been questioned under caution.
"The investigation into circumstances surrounding events in Gloucestershire is hugely complex, and our specialist teams are interrogating multiple lines of enquiry," Britain's Senior National Coordinator for Counter Terrorism Policing, Vicki Evans, said in a statement.
"As we’ve made clear, we’re looking at all possible angles – including possible foreign state involvement."