LONDON (AP) — British police on Tuesday arrested a 22-year-old man in London on suspicion of a terror offense over a security incident at a U.S.-run military air base in England that authorities have linked to Iran.

Counter Terrorism Policing said the man, a British national, was detained in the Westminster area of central London on suspicion of preparation of terrorist acts.

The arrest is the seventh in connection with a suspected plot against RAF Fairford in western England, which has been used by American bombers to strike Iran.

Six other men have been released on bail under investigation.

Scores of residents were evacuated from their homes near the base early on Sept. 27 as armed police officers and army bomb-disposal experts swooped on the rural area. Police later said they had found a quantity of an accelerant – gasoline – in three vans linked to the five suspects, but no explosives.

Prime Minister Andy Burnham has said the U.K. sees “strong indications” that Iran played a part in the incident

Vicki Evans, the senior national coordinator for counterterrorism policing said detectives “continue to pursue multiple lines of enquiry” and “remain committed to investigating all possible angles.”