Terrorists could be made to take a lie detector test to prove they have reformed and are not planning to carry out another attack.

Plans to introduce “polygraph testing” were announced by the Government as part of a wave of measures being described as a “major overhaul” in the way terrorists are punished and monitored, including tougher sentences to see them locked up for longer.

It is understood there are hopes that terrorists who are going to be out on licence could be made to take the test in a similar way to which sex offenders are sometimes questioned to check their behaviour.

More details of The Counter Terrorism (Sentencing and Release) Bill have been released after plans for change were put in place in the wake of the latest London Bridge attack and later announced during the Queen’s Speech.

It is less than two months since convicted terrorist Usman Khan embarked on a killing spree armed with two knives and wearing a fake suicide vest after attending a prisoner rehabilitation programme near London Bridge.

Describing the move as a “major shift” in the UK’s approach to the sentencing and management of terrorist offenders, the announcement from the Home Office and the Ministry of Justice (MoJ) also promised to:

– Force dangerous terrorists who receive extended determinate sentences to serve the whole time behind bars.

– Ensure those convicted of serious offences such as preparing acts of terrorism or directing a terrorist organisation would have to spend a minimum of 14 years in jail.

– Scrap early release from jail for those classed as dangerous and handed extended determinate sentences – in which criminals have to spend longer on licence after prison.

– Double the number of counter-terrorism probation officers.

– Make more places available in probation hostels so authorities can monitor terrorists in the weeks after they are released from prison.

– Increase counter-terrorism policing funding by £90 million year on year for the coming year to £906 million.

– Give an immediate £500,000 cash injection for support for victims of terrorism and a review of services available.

– Provide more specialist psychologists and trained imams who help to assess the risk of radicalised offenders.

– Offer more training for frontline prison and probation staff to identify and challenge extremism behind bars and on licence.

Terrorism-related arrests in Great Britain
(PA Graphics)

Terrorists deemed not to be a risk would have to serve two-thirds of their sentence before the Parole Board could consider them for release.

Jonathan Hall QC, the independent reviewer of terrorism legislation, will also review the way in which agencies like the police, probation and security services investigate and monitor terrorists – known as Multi Agency Public Protection Arrangements (Mappa).

Home Secretary Priti Patel said: “The senseless terror attack at Fishmongers’ Hall in November confronted us with some hard truths about how we deal with terrorist offenders, which is why we immediately announced a review into sentencing and licence conditions, to do whatever is necessary to stop these sickening attacks from taking place.

“Today we are delivering on those promises.”

Justice Secretary Robert Buckland defended the use of lie detectors in assessing offenders’ risk to the public after questions were raised over their accuracy and appropriateness in the criminal justice system.

“We get a lot of people who are superficially very compliant with the regime and sometimes the assessment of risk is a really difficult thing to do,” he told Sky News.

“You can get people who are, in effect, sleepers for many years and then suddenly back come the hatreds and the prejudices and we see atrocities like the one we did at Fishmongers’ Hall.

“Which is why, I think, the introduction of polygraphs, the lie-testing devices which are already being used in sex offenders, improves the tools that we have in terms of trying to assess that risk, to minimise that risk.”

Plans for the Bill were first mooted shortly after the November attack, which claimed the lives of Saskia Jones and Jack Merritt.

At the time, Mr Merritt’s father, Dave, hit out at Boris Johnson, accusing him of seeing an opportunity to score political points during the general election in the aftermath of the tragedy.

Incident on London Bridge
Jack Merritt and Saskia Jones both were killed in the London Bridge attack (Metropolitan Police/PA)

Asked about the father’s concerns, Mr Buckland said he makes “no apology for putting public protection at the top of the agenda”.

“I take on board the point that there are some people capable of rehabilitation but, as I said at the time, there are sadly others who are not,” the Cabinet minister told BBC Breakfast.

“And therefore this package is not just about the sentencing regime, it’s about what you do in our prisons with regard to either dealing with the risk of terrorism or reducing the risk through programmes of rehabilitation and addressing the causes of extremism.”

Khan, a 28-year-old British national from Staffordshire, had been released from prison on licence in December 2018, halfway through a 16-year prison sentence after he was convicted of terror offences in February 2012.

He was part of an al Qaida-inspired terror group, linked to radical preacher Anjem Choudary, that plotted to bomb the London Stock Exchange and build a terrorist training camp on land in Pakistan-controlled Kashmir owned by his family.

Staffordshire Police are being investigated by the Independent Office for Police Conduct for their role in managing Khan.

In the year to the end of September, there were 44 convictions for terrorism offences, with 17 offenders being sent to jail for between four and 10 years, the Government said.

Five were jailed for 10 years or more and one was handed a life sentence.

Around 245 convicted terrorists were freed from jail between 2012 and 2019.

Incident on London Bridge
Plans were put in place in the wake of the latest London Bridge attack (Dominic Lipinski/PA)

Shadow home secretary Diane Abbott said the announcement of a security overhaul was “an admission of failure” by the Government.

“Major terrorist outrages have occurred all too frequently, including attacks by perpetrators who were known to the security services,” she said.

Liberal Democrat home affairs spokeswoman Christine Jardine said judges already had the power to lock up terrorists for life while polygraphs were “not accurate or reliable enough” for such critical decisions.

“We will continue to oppose authoritarian laws that do little to make us safer, but a lot to undermine essential British freedoms,” she said.