A 17-year-old boy has been arrested in the investigation into the Parsons’ Green attack.
The teenager, arrested in Thornton Heath, south London around 12.05am, was detained under section 41 of the Terrorism Act..
Meanwhile officers began a search of the property where the teen was arrested.
This brings the total arrested over the incident up to six.
Commander Dean Haydon, head of the Met’s Counter Terrorism Command, said: “This continues to be a fast-moving investigation. A significant amount of activity has taken place since the attack on Friday.
“We now have six males in custody and searches are continuing at five addresses. Detectives are carrying out extensive inquiries to determine the full facts behind the attack.”
The investigation into the rush hour bombing has seen three men aged 25, 30 and 48, detained in Newport, south Wales, a 21-year-old named Yahyah Farroukh arrested in Hounslow, west London, and an 18-year-old man detained at the Port of Dover.
A time limit on Farroukh’s detention is expected to expire today, while detectives have been given until Saturday to continue questioning the 18-year-old suspect.
Some 30 people were injured when a homemade bomb partially exploded on the District Line last Friday.