Prime Minister Theresa May chaired a meeting of the emergency COBRA committee, in the afternoon as Britain's terror threat remained at severe, meaning a terror attack was highly likely. It did not provide any further details on the man's identity or potential connection to the attack.
This it Britain's fifth terror attack this year, but it's the only one that hasn't caused fatalities.
Saturday's "arrest will lead to more activity from our officers", police said. ISIS was also behind the London Bridge Attack in June, which saw eight people, plus three terrorists, killed. The police said that the arrest was a "significant" development and that the investigation is advancing well.
Mr Basu said in a statement: "The public should remain vigilant as our staff, officers and partners continue to work through this complex investigation".
Police said a device was placed inside a bag and left by the tube carriage door before exploding towards the rear of the train, filling the carriage with smoke.
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He is not completely at his best, but he is getting there. "I don't give the team out today, I will give it out on Thursday". Arsenal will compete in the Europa League where they are in Group H with FC Cologne, Bate Borisov and Red Star Belgrade.
The threat level was last raised to critical following the Manchester Arena bombing in May, when 23 people, including the attacker, were killed as they exited a concert by United States popstar Ariana Grande.
The move comes after a bomb exploded on the Parsons Green Tube yesterday.
'I am sure I speak for London when I say we are incredibly grateful to the police and intelligence services for doing everything possible to keep Londoners safe'.
The train hit by the bomber had video cameras in each auto, and the London Underground network has thousands of cameras at the entrances to stations and along the labyrinth of subterranean and aboveground passageways leading from the entryway to the trains.