An 18-year-old man has been arrested in connection with the Parsons Green Tube bombing that left 30 people injured.
Metropolitan Police Deputy Assistant Commissioner Neil Basu described the arrest in Dover, Kent, as “significant”, but added: “Although we are pleased with the progress made, this investigation continues and the threat level remains at critical.”
The teenager was held on suspicion of a terror offence in the port area of the town, which is the busiest ferry hub in Europe and serves as a commercial gateway to the French coast.
He will be moved to a south London police station “in due course”.
The explosion happened during the Friday morning rush hour as the District Line train was pulling into the west London station, which has since reopened.
Sky sources say the device, which was inside a bucket concealed within a supermarket carrier bag, had a timer and failed to fully detonate.