An urgent review of the licence conditions of people jailed for terror offences has been launched by the Ministry of Justice following Friday’s London Bridge attack.
Two people were killed and three were injured by Usman Khan, 28, a convicted terrorist who served half of his time.
PM Boris Johnson claimed scrapping early release would have stopped him.
But Labour leader Jeremy Corbyn will blame budget cuts for “missed chances to intervene” in a speech on Sunday.
As many as 70 people convicted of terror offences who have been released from prison could be the focus of the government review.
Khan, 28, who was shot by police on Friday after carrying out the attack, was jailed over a plot to bomb the London Stock Exchange in 2012.
He was sentenced to indeterminate detention for “public protection” with a minimum jail term of eight years.
This sentence would have allowed him to be kept in prison beyond the minimum term.
But in 2013, the Court of Appeal quashed the sentence, replacing it with a 16-year-fixed term of which Khan should serve half in prison. He was released on licence in December 2018 – subject to an “extensive list of licence conditions”, Met Police Assistant Commissioner Neil Basu said.
“To the best of my knowledge, he was complying with those conditions,” he added.
As part of his release conditions, Khan was obliged to take part in the government’s desistance and disengagement programme, which aims to rehabilitate people who have been involved in terrorism.
Khan was living in Stafford and wearing a GPS police tag when he launched his attack inside Fishmongers’ Hall, where he was attending a conference hosted by Learning Together, a prisoners’ rehabilitation programme.
The attack then continued onto London Bridge itself.
Khan had taken part in the Learning Together scheme while in prison and was one of dozens of people – including students and offenders – at the event.
He appeared as a “case study” in a report by the initiative. Identified only as “Usman”, Khan was said to have given a speech at a fundraising dinner after being released from prison.
He was also given a “secure” laptop that complied with his licence conditions, to allow him to continue the writing and studying he began while in jail.
Khan contributed a poem to a separate brochure, in which he expressed gratitude for the laptop, adding: “I cannot send enough thanks to the entire Learning Together team and all those who continue to support this wonderful community.”
Jack Merritt, a course co-ordinator for Learning Together from Cambridge, was one of two people fatally stabbed on Friday.
A woman who also died has not yet been named.
NHS chief executive Simon Stevens said three victims remained in hospital following the attack – two in a stable condition and one with less serious injuries.
Mr Basu said officers had been working “flat out” to try to establish the “full circumstances” of the stabbing.
On a visit to the attack site, the prime minister said the practice of cutting jail sentences in half and letting violent offenders out early “simply isn’t working”.
Mr Johnson vowed to “toughen up sentences” if the Conservatives win the general election on 12 December.
“If you are convicted of a serious terrorist offence, there should be a mandatory minimum sentence of 14 years – and some should never be released,” he said.
“Further, for all terrorism and extremist offences, the sentence announced by the judge must be the time actually served – these criminals must serve every day of their sentence, with no exceptions.”
Speaking to Sky’s Sophy Ridge on Sunday, Labour leader Jeremy Corbyn said the police had “no choice” but to shoot Khan dead, saying they were “stuck with a situation where there was a credible threat of a bomb belt around his body”.
Mr Corbyn also said terrorists should “not necessarily” serve their full sentences automatically, but that it “depends on circumstances”.
Jonathan Hall QC, independent reviewer of terrorism legislation, told BBC Breakfast it was difficult to speculate on what measures might have prevented the attack, which he described as “low sophistication” and therefore “highly difficult to detect and to prevent”.
How the law on early release changed
2003 – The Criminal Justice Act meant most offenders would be automatically released halfway through sentences, but the most “dangerous” would have their cases looked at by a Parole Board. Sentences with no fixed end point, called Imprisonment for Public Protection (IPP), were also introduced.
2008 – Criminal Justice and Immigration Act removed review process by Parole Boards, meaning more offenders were released automatically halfway through sentences. Judges could still hand down life sentences or IPPs for dangerous offenders.
2012 – Usman Khan was handed a sentence with no fixed end date because of the risk he posed to the public. In the same year, the Legal Aid, Sentencing and Punishment of Offenders Act scrapped IPPs and reintroduced the role of the Parole Board for extended sentences of 10 years or more – this time after two-thirds of the sentence has passed. But that did not mean those already serving IPPs would have them lifted.
2013 – During an appeal, Lord Justice Leveson ruled that Khan’s indeterminate sentence should be substituted for an extended sentence with automatic release at the halfway point.
A row erupted on Saturday between Home Secretary Priti Patel and former Labour government minister Yvette Cooper over Khan’s early release.
Ms Cooper said the government was “warned about the risks” of ending Imprisonment for Public Protection (IPP) – which was introduced by Labour to protect the public from dangerous prisoners, but was scrapped by the coalition government in 2012.
But Ms Patel blamed the Criminal Justice and Immigration Act brought in by Labour in 2008, and said the law was changed “to end Labour’s automatic release policy”.