Security was stepped up after a suspicious item was discovered on a Tube train. (Representational image)
Security was stepped up Saturday on the London Underground network as police questioned a 19-year-old man arrested under anti-terror laws after a suspicious item was discovered on a Tube train.
"The public will see more officers, including armed police, in and around transport hubs," a Scotland Yard spokesman told AFP.
The item, found Thursday on a train at North Greenwich station, which serves the O2 entertainment complex in southeast London, was being forensically examined.
Counter-terror officers attended an address in Newton Abbott in southwest England on Saturday as part of the inquiry and "found an item they deemed suspicious", Scotland Yard said.
Those officers evacuated the address, erected a 200-metre cordon around it, and the local police force is now dealing with the suspicious item.
The 19-year-old arrested on Friday remains in custody for questioning on suspicion of the commission, preparation and instigation of terrorism acts.
Armed police arrested him in London in connection with the suspicious package found at North Greenwich station.
An electric stun gun was used during the arrest on a busy shopping street, but no shots were fired.
Britain's current national terror threat level has been set at severe -- the fourth-highest of five -- since August 2014, meaning an attack is considered highly likely.
The Times newspaper spoke of a "lone wolf" and said that the incident was "feared to be the first credible bombing attempt on the London transport network in more than 10 years".
Scotland Yard refused to comment on the report.