Detectives investigating the train bombing that injured 29 people in London have arrested an 18-year-old man on suspicion of a terror offence.
Scotland Yard says he was detained in the port area of Dover.
The police say he will be moved to a south London police station.
They say the arrest is significant but their investigation continues and the threat level remains at critical
Earlier, Prime Minister Bill English said a New Zealander is among the 29 people injured in the bombing.
New Scotland Yard said it appeared an improvised explosive with a timer was set off at Parsons Green station in the south west of the British capital during rush hour yesterday.
Witnesses described seeing a fireball filling the carriage, with passengers suffering burns, as well as other minor injuries during the rush to escape.
UK Prime Minister Theresa May said the terrorism threat has now been raised to critical, meaning an attack is expected imminently.
Islamic State has claimed responsibility for the attack and a hunt is underway for the person who planted the device.
Speaking on the campaign trail in Rotorua, Mr English said one New Zealander had been caught up on the attack, and had been taken to hospital, treated and discharged.
"So it's great news that the Kiwi ... is not seriously injured.
"Officials have yet to talk to the person themselves, but I think they have heard from their family, so there will be more details [coming] through."
"For Kiwis in London, it's a place that has mastered the art of being on high alert while they go about their daily life.
"I think Kiwi's who are there know the element of risk being in a place that's become a target," Mr English said.