A FORMER Cobra chief says all British citizens feared to have been radicalised should be imprisoned without trial - even if there isn't enough evidence to prosecute them.
Colonel Richard Kemp also said non-Brits suspected of extremism should be instantly deported, and anyone trying to return to the UK from Syria barred from entering the country.
Retired Army commander Colonel Kemp - who led the Army in Afghanistan in 2003 - told Good Morning Britain: "We have the finest intelligence services and the finest police force, they have protected us from this kind of attack time and time again.
"The problem is there are 3,000 known jihadists on the streets of the UK today.
"Our intelligence services and police - no matter how good they are - cannot monitor all of them, they can't control all of them.
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"People like the bomber in Manchester and the attacker in Westminster... were known to the security services, yet they slipped through the net.
"They have to prioritise and they sometimes get it wrong. It's not their fault.
"We need to help them... by removing as many of these people out of this country as we possibly can.
"Every single person who we have intelligence upon, who is known to be involved in terrorism, who is not a UK citizen and who we cannot prosecute in the court, we get rid of out of this country. We deport them, we send them back to where they came from.
"We do not allow them to roam free on our streets and murder, maim and disfigure our children in the way they did in Manchester."
When presenter Kate Garraway pointed out that the Manchester bomber was British, Colonel Kemp said: "We intern him if he can't be deported.
"We don't just throw him in jail, we don't do it on the say-so of a politician or a police officer.
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"We do it on the say-so of a senior judge who goes through a judicial process, who's presented with the intelligence.
"If the case is strong enough to convince the judge, he is then interned without trial."
Steve Howe, the husband of Alison Howe who was killed in Monday's attack, also told GMB that Britain needed to be tougher on extremists.
Several people are still missing after the attack, which killed 22 and injured 119 including children.
A bomb factory has reportedly been found in the Manchester home of suicide attacker Salman Abedi, who was just 22.