Boris Johnson and Sadiq Khan have sent their support to the injured and affected in the Streatham terror attack.
Now Prime Minister Johnson wants to know why the twisted knifeman, from Harrow, served only half his three year jail term for terror offences.
On Monday, the Tory leader will announce new plans on how to deal with brainwashed jihadis.
A source said: “The public will look at this case and say ‘why wasn’t this individual kept behind bars?’ and the PM shares that view.
“The PM’s put forward some plans already. This shines a spotlight on something else, which is people who were sentenced at the lower end of the spectrum who are entitled to automatic release at the halfway point.”
The police and Home Office were worried Amman’s “language would suggest that he continued to hold extremist views”, it was claimed.
This comes as Mr Johnson thanked the emergency services after the extremist was shot and killed by anti-terror cops.
The PM said his thoughts were with those wounded and affected by the incident in South London.
He tweeted: “Thank you to all emergency services responding to the incident in Streatham, which the police have now declared as terrorism-related.
“My thoughts are with the injured victims and their loved ones following today’s horrific attack in Streatham.
“I want to pay tribute to the speed and bravery of the police who responded and confronted the attacker – preventing further injuries and violence – and all of the emergency services who came to the aid of others.
“An investigation is taking place at pace to establish the full facts of what happened, and the Government will provide all necessary support to the police and security services as this work goes on.
“Following the awful events at Fishmonger’s Hall in December, we have moved quickly to introduce a package of measures to strengthen every element of our response to terrorism – including longer prison sentences and more money for the police.
“Tomorrow, we will announce further plans for fundamental changes to the system for dealing with those convicted of terrorism offences.”