British counter-terrorism officers have made another arrest as they investigate suspicious activity near RAF Fairford in Gloucestershire.
Police said a 27-year-old man who holds both British and Iranian nationality was arrested in Westminster, London, on suspicion of preparing terrorist acts under Section 5 of the Terrorism Act 2006.
A second man, a 26-year-old British national, has also been questioned under caution. Officers have carried out searches at two properties in the London area.
The latest development comes days after five British men in their 20s were arrested near RAF Fairford. Those five men remain on police bail while detectives continue their investigation.
The original incident began after police received information about three vehicles travelling towards the airbase in the early hours of Sunday, September 27.
Investigators later confirmed that petrol had been found in vehicles linked to the suspects, but no improvised explosive device was discovered.
Counter Terrorism Policing said the investigation is complex and that officers are following several lines of inquiry.
Police have also said they are examining every possible explanation, including the possibility of foreign-state involvement.
There have been claims of a possible Iranian connection, but no final conclusion has been announced by investigators. Iran has denied involvement in the incident.
RAF Fairford is a major military facility in Gloucestershire and has been used by US military aircraft.
Police say the investigation remains ongoing and are appealing to anyone with relevant information to come forward.