The UK is under threat from up to 4,000 "home-grown" terror suspects across the country, the head of Metropolitan Police has warned. Commissioner Sir Bernard Hogan-Howe also disclosed that a "very significant" number of the radicals were based in London.
"We believe our security services have a very good handle on them. [There are] Three to four thousands across the whole of the UK, but very significant numbers in London. Therefore, we have to keep an eye on them and that demands resources," the police chief told LBC Radio on 17 November.
He added: "You can't look at them all of the time. You have to prioritise. As we have seen in France and Belgium, it's not easy to predict where someone who has started to become radical, moves to a position where they are going to do something."
Hogan-Howe's comments come in the wake of the Islamic State (Isis) linked attacks on Paris, which have left at least 129 dead and hundreds more injured.
David Cameron has promised to boost the numbers of the British intelligence agencies after the horrific incident, but the commissioner argued that resourcing was essential as the force faces cuts.
"I think this type of attack [in Paris] shows the police have got to be ready, flexible, and have enough reserves," Hogan-Howe added. The top officer is leading a review of his service in reaction to the massacre in the French capital.
The police presence across London has been stepped up and the public have been urged to be vigilant in the wake of the attacks across the English Channel.
Meanwhile, Labour leader Jeremy Corbyn faces criticism from his own party after opposing a so-called "shoot-to-kill" policy. The left-winger said he was "unhappy" with the strategy but Hogan-Howe stressed that the law gave armed officers the ability to use reasonable force if someone's life was in danger.