British counter-terrorism police arrested a 27-year-old dual UK-Iranian national in Westminster on Thursday afternoon on suspicion of preparing terrorist acts under the Terrorism Act 2006. The arrest forms part of an ongoing investigation into suspicious activity near RAF Fairford in Gloucestershire over the weekend.

Five British men in their 20s from London were detained early Sunday after a resident reported three suspicious vans and a group of masked men near the base in the village of Whelford. The men, initially held on explosives suspicions, were later released on bail with strict conditions after no explosives were found, though police recovered petrol. Officers have searched two London properties in connection with the case.

Prime Minister Andy Burnham stated there are strong indications of Iranian involvement in the incident. Israeli Prime Minister Benjamin Netanyahu said Israel had warned UK authorities in advance of a potential Iranian-sponsored attack on the base. US President Donald Trump and Secretary of State Marco Rubio also referenced possible foreign actor involvement.

Iran's embassy in London has categorically rejected any connection, calling the suggestions unfounded and malicious. The base has faced heightened tensions since Iran's Revolutionary Guards described it as a legitimate target earlier this year.

The investigation remains active, with authorities examining all lines of inquiry including potential foreign state links. RAF Fairford hosts US aircraft and has been central to operations in the region.