Emergency legislation is needed to make sure terrorists are not released automatically from prison half way through their sentence, the Justice Secretary has said.

Speaking in the wake of the latest terror attack in Streatham, Robert Buckland also said the Parole Board should review cases before such offenders are freed.

Sudesh Amman was shot dead by police after grabbing a knife from a shop and attacking two bystanders in Streatham High Road, south London, on Sunday. A third person was injured by flying glass during the gunfire.

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Mr Buckland told the House of Commons on Monday afternoon: “Yesterday’s appalling incident makes the case plainly for immediate action.

“We cannot have the situation, as we saw tragically in yesterday’s case, where an offender – a known risk to innocent members of the public – is released early by automatic process of law without any oversight by the Parole Board.

“We will be doing everything we can to protect the public, that is our primary duty.

“We will, therefore, introduce emergency legislation to ensure an end to terrorist offenders getting released automatically having served half of their sentence with no check or review.”

The 20-year-old, who was jailed for possessing and distributing terrorist documents in December 2018, was freed from prison less than a fortnight ago and had been staying at a bail hostel in nearby Leigham Court Road.

Scotland Yard said armed officers were following Amman on foot as part of a “proactive counter-terrorism surveillance operation” in Streatham High Road.

The three victims were taken by ambulance to south London hospitals.

One man, in his 40s, is no longer considered to be in a life-threatening condition following treatment, police said.

A woman in her 50s, a teacher at a nearby school, had non-life threatening injuries and has been discharged from hospital.

Police said a second woman, in her 20s, who suffered minor injuries believed to have been caused by glass following the discharge of a police firearm, continues to receive treatment.

Investigations continue with officers also searching two addresses in south London and Bishop’s Stortford, Hertfordshire.

Mr Buckland added: “We face an unprecedented situation of severe gravity and, as such, it demands that the Government responds immediately and that this legislation will therefore also apply to serving prisoners.”

He said offenders will not be considered for release until they have served two-thirds of their sentence and that no terrorists will be released before the end of their full custodial term unless the Parole Board agrees.

The Parole Board would be “strengthened” to deal more effectively with the risks that terrorists pose and steps would be taking to introduce the plans “as soon as possible”, Mr Buckland said.

The Government will also consider making new legislation to ensure that extremists are more closely monitored on release and will review whether the current maximum sentences for terrorist offences are sufficient.

The atrocity follows the attack at Fishmongers’ Hall in the City of London in November, when another convicted terrorist, Usman Khan, murdered two people despite being on probation.

Cambridge graduates Jack Merritt, 25, and Saskia Jones, 23, were stabbed to death at the rehabilitation conference.

This prompted a raft of measures to be proposed including forcing dangerous terrorists who receive extended determinate sentences to serve the whole time behind bars.

The Counter Terrorism (Sentencing and Release) Bill, which is yet to be fully debated in Parliament, would also ensure those convicted of serious offences, such as preparing acts of terrorism or directing a terrorist organisation, would spend a minimum of 14 years in jail, introduce lie-detector tests for offenders and double the number of counter-terrorism probation officers.

READ MORE: Man shot dead in London was convicted terrorist

IS supporter Amman, who at the time of his sentencing was 18 and living in Harrow, smirked as he was jailed for three years and four months at the Old Bailey.

The court heard that he had listed dying a martyr as one of his “life goals” and had posted al Qaida propaganda on a family WhatsApp group, exposing siblings as young as 11 to graphic material.

His stash of manuals on bomb-making, knife-fighting and close combat included the titles Bloody Brazilian Knife Fighting and How To Make A Bomb In Your Kitchen.