British police have arrested a seventh man in connection with a suspected terrorist plot near RAF Fairford, a U.S.-used military base in England. 

The 22-year-old British national was detained in London on suspicion of preparing terrorist acts, as investigators continue examining the September 27 incident.

Six other men previously arrested in the case have been released on bail while remaining under investigation.

Police found gasoline in three vans linked to earlier suspects but no explosives, and authorities have not publicly detailed the suspected plot’s exact objective, CBS News has reported.

The investigation has been linked by British officials to possible Iranian involvement, which Iran denies, while the U.S. has removed its bombers from RAF Fairford following reported threats.