Britain's two main political parties are blaming each other for the early release of the London Bridge terrorist attacker, Usman Khan, who killed two people in a frenzied knife attack in the capital on Friday.
A row has broken out between the Conservatives and the Labour party after it emerged that Khan, 28, had been jailed in 2012 for plotting to bomb the London Stock Exchange but was automatically released halfway through his prison sentence a year ago.
Labour leader Jeremy Corbyn criticised the government's sentencing policies and called for "a very full investigation". His comments come days before a general election on December 12 where he is looking to replace Prime Minister Boris Johnson.
"I think there is also a question about what the probation service were doing ... and whether the parole board should have been involved in deciding whether or not he should have been allowed to be released from prison in the first place," he said on Saturday.
Later that day, Mr Johnson said that if his party wins a majority in the election, terrorists will serve their entire sentences and no longer be eligible for early release. He added that they must spend at least 14 years in jail.
Meanwhile Home Secretary Priti Patel blamed the previous Labour government for Khan's early release after Labour MP and former shadow home secretary Yvette Cooper asked how the extremist could have been released when he was considered so dangerous.
Ms Cooper said on Twitter: “Usman Khan was sentenced for serious terror offence in Feb 2012. Thought to be so dangerous by judge he was given IPP [Imprisonment for Public Protection] sentence to prevent release if still serious threat.
“Instead he was released six years later without Parole Board assessment. How could this be allowed to happen?”
The home secretary responded by blaming a law brought in under the Labour government in 2008.
"Conservatives changed the law in 2012 to end your automatic release policy by Khan was convicted for this," she said.
On Friday Khan unleashed a frenzied knife attack at a criminal justice conference fatally wounding a man and a woman and leaving three others seriously injured until members of the public managed to disarm him.
He had been at an event at Fishmongers Hall next to London Bridge prior to the attack where a Cambridge University conference on prisoner rehabilitation called Learning Together was being held.
One of the victims was identified on Saturday as Jack Merritt, a 25-year-old Cambridge graduate who was the course co-ordinator for Learning Together.
ISIS claimed responsibility for the attack in a message released through its online propaganda agency Amaq late on Saturday, saying it was carried out by one of its fighters.
The statement from the terror group said that Khan was "responding to calls to target the nationals of Coalition countries," a phrase lifted from a famous speech given by Abu Muhammad al-Adnani, the group’s former spokesman.
The news comes as the UK’s Home Office has faced damning criticism over its failures to prevent the 2017 Manchester Arena bombing, which killed 22 people and injured over 100 more, and the Parsons Green train explosion which wounded more than 50 people.
In both cases the attackers had been on the radar of the security services and the government’s anti-extremism Prevent programme.
London Mayor Sadiq Khan said “big questions” need to be answered about Khan’s release.
It comes as the terrorist was identified as a student and friend of notorious UK hate preacher Anjem Choudary.
In 2012 a judge ruled that Khan was a danger to society and had given him an indefinite Imprisonment for Public Protection (IPP) sentence – under the scheme dangerous offenders were not released until the authorities deem them to no longer be a threat to society.
When the initiative was scrapped, Khan was resentenced to 16 years and was released automatically after eight years last December.
At the time Lord Justice Leveson told Khan: “There is no doubt that anyone convicted of this type of offence could legitimately be considered dangerous.
“There is an argument for concluding that anyone convicted of such an offence should be incentivised to demonstrate that he can safely be released; such a decision is then better left to the Parole Board for consideration proximate in time to the date when release becomes possible.”
However, on Saturday the UK’s Parole Board was quick to distance itself from the decision to release Khan.
“We have every sympathy with those affected by the dreadful events that happened in London Bridge yesterday,” it said in a statement.
“Given the seriousness of this attack, it is understandable that there is speculation about the attacker's release from prison.
"The Parole Board can confirm it had no involvement with the release of the individual identified as the attacker, who appears to have been released automatically on licence (as required by law), without ever being referred to the Board."
Mr Khan said the law needs to be changed to prevent dangerous offenders from being automatically released.
He said: “A man like this who was convicted of a serious offence shouldn’t be able to be released automatically.
"I voted against the government getting rid of the IPP sentence. The judges need more tools.
“When a person is released on licence, does the Ministry of Justice and the probation service have the resources to supervise people who are clearly dangerous?”
One of the key issues ahead of the UK election has been the time prisoners serve in jail, prior to the attack Mr Johnson was calling for offenders to serve longer sentences.
On Friday Mr Johnson reiterated his concerns and said it was a “mistake” for Khan to have been released.
“It is a mistake to allow serious and violent criminals to come out of prison early and it is very important that we get out of that habit and that we enforce the appropriate sentences for dangerous criminals, especially for terrorists, that I think the public will want to see,” he said.
He called a meeting of the Government's emergency committee Cobra to address the attack.
Terrorism lawyer Paul Genney told The National: "It is clear that dangerous offenders should be made to serve their full sentences. If this man had been serving the full 16 years handed to him then this atrocity would not have happened.
“Urgent questions need to be asked in Downing Street over why he was not being heavily supervised. There have been substantial failings here.”
Security minister Brandon Lewis has refused to say whether the attack showed a “failure” by authorities and said it would be “inappropriate and dangerous” to speculate.
The authorities have previously raided Khan’s home over his links to Choudary.
Choudary is cited as being responsible for the indoctrination of hundreds of ISIS followers across Europe.
He had attended protests by the banned Al-Muhajiroun group prior to his arrest.
Dr Paul Stott, a research fellow at the Centre on Radicalisation and Terrorism at Henry Jackson Society, told the Telegraph: "Usman Khan was a loyal and integral member of Choudary's inner-circle and we know him to have been highly regarded by Choudary."
Despite calls to tighten up the criminal justice system, it emerged that some of the selfless heroes responsible for apprehending him were also convicted criminals.
One man James Ford was on day-release from his life sentence for strangling a young woman when he aided in Khan’s capture.
On Saturday the Queen praised the actions of those involved.
“Prince Philip and I have been saddened to hear of the terror attacks at London Bridge,” she said.
“We send our thoughts, prayers and deepest sympathies to all those who have lost loved ones and who have been affected by yesterday's terrible violence.
“I express my enduring thanks to the police and emergency services, as well as the brave individuals who put their own lives at risk to selflessly help and protect others.”
The UAE condemned the attack and expressed "solidarity with the UK against all forms of violence, terrorism, and extremism".
Khan had strapped a fake bomb to his chest during the attack, which saw brave bystanders tackling him to the ground despite the threat to their own lives.
They held on to him until police arrived and shot him, killing him instantly.
The incident happened at 2pm on Friday at the Fishmongers Hall next to London Bridge where a Cambridge University conference on prisoner rehabilitation called Learning Together was being held.
Two people died from stab wounds and three others were injured in the incident.
Khan, from Staffordshire, has a history of terror offending, when he was arrested in 2012 police discovered a list of possible targets which included the homes of then London Mayor Mr Johnson, the Dean of St Paul's Cathedral and two rabbis.
Security has been increased in London ahead of the Nato summit next week.