A 22-year-old British national was arrested in Westminster, London, on Tuesday on suspicion of preparation of terrorist acts, in connection with last month's incident near RAF Fairford, the U.S.-used air base in Gloucestershire. It is the seventh arrest in the investigation.

The six other people arrested earlier in the probe have been released on bail, police said. The investigation followed a suspected terror plot involving drones near the base, which hosts U.S. military assets.

The United States moved B-1 bombers out of RAF Fairford in the wake of the suspected plot, underscoring the seriousness with which both governments are treating the incident. The arrested man remains in custody.