London Bridge killer Usman Khan was convicted terrorist recently freed from jail

The knife-wielding London Bridge attacker has been revealed as a convicted terrorist jailed over a plot to bomb the London Stock Exchange.

Usman Khan, 28, killed a man and a woman and injured three people, including a man and two women, during his rampage on Friday afternoon.

In February 2012, he was handed an indeterminate jail sentence over a terror plot, with the sentencing judge saying he should not be released until he was no longer a threat to the public.

However, this sentence was quashed at the Court of Appeal in April 2013 and he was given a 16-year jail term.

Khan was released from prison in December 2018 on licence, having served eight years of his sentence - including time spend on remand.

Fake suicide vest

Police believe the terror attack on Friday began at Fishmongers' Hall, where Khan had been attending a conference on prisoner rehabilitation. Khan, who was wearing a fake suicide vest, reportedly threatened to "blow up" the building.

The rampage continued on London Bridge, where several members of the public chased and disarmed Khan.

Footage from the scene shows one man spraying the attacker with a fire extinguisher, while another brandishes the tusk of a Narwhal whale.

Khan was dragged to the ground and seconds after police pulled a man off him, officers shot the terrorist dead at point-blank range in full view of horrified onlookers.

A plain-clothed police officer was among those who had pounced on Khan. He was filmed backing away while holding a large knife, apparently wrestled from the attacker.

Terrorist training camp

As well as plotting to blow up the London Stock Exchange in 2012, Khan and eight accomplices planned to build a terrorist training camp on land in Pakistan-controlled Kashmir owned by his family.

Sky's Home Affairs correspondent Mark White has been told by sources that Khan was being monitored with an electronic tag when he was released from jail a year ago and had links to Islamist terror groups.

He was a student and personal friend of the Islamist extremist Anjem Choudary, who co-founded the now banned Al-Muhajiroun group.

Khan was one of a series of Al-Muhajiroun connected terrorists to be released over a six-month period beginning in the autumn of 2018.

Khan was known to have attended a series of Al-Muhajiroun protests and street stalls in the Midlands area prior to his arrest.

In the months before his arrest and conviction for the London Stock Exchange terror plot, police raided his home in Tunstall, Staffordshire, over concerns about his links to Choudary.

At the time of his arrest, investigators found Choudary's phone details on Khan's mobile phone.

Before his conviction in 2012, Khan had been secretly recorded talking about plans to recruit UK radicals to train at a camp in Kashmir.

"There's victory, what we hope for, there's shahada (death as martyrs), or there's prison," he had said.

The then-20-year-old pleaded guilty to engaging in conduct for the preparation of terrorism, which included travelling to and attending operational meetings, fundraising for terrorist training, preparing to travel abroad and assisting others in travelling abroad.

Passing sentence, Mr Justice Wilkie said Khan and his co-conspirators had planned a "serious, long-term venture in terrorism" that could have resulted in atrocities in the UK.

"It was envisaged by them all that ultimately they and the other recruits may return to the UK as trained and experienced terrorists available to perform terrorist attacks in this country, on one possibility contemplated in the context of the return of British troops from Afghanistan," he said.

The Parole Board has said it had no part in Khan's release from prison.

Attack investigation

The Met's assistant commissioner Neil Basu said Khan had been living in Staffordshire before Friday's attack and officers were searching his address.

He added: "This individual was known to authorities, having been convicted in 2012 for terrorism offences. He was released from prison in December 2018 on licence and clearly, a key line of enquiry now is to establish how he came to carry out this attack."

He said: "The investigation into the attack near London Bridge continues at a pace.

"Whilst we are still in the early stages of the investigation, at this time we are not actively seeking anyone else in relation to the attack.

"However, we continue to make fast time enquiries to ensure that no other people were involved in this attack and that there is no outstanding threat to the public."

The prime minister has called for an end to serious and violent criminals being released early from prison.

Speaking before chairing a meeting of the government's emergency committee Cobra, Boris Johnson said he had "long argued" that 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".

Mr Johnson added that more police would be patrolling the streets in the coming days for reassurance purposes.

'Big questions need to be answered'

London mayor Sadiq Khan told Sky News there are "big questions that need to be answered" about the attacker's release because "it affects other people as well who may be a source of concern for many of us".

He said: "One of the important tools judges had when it came to dealing with dangerous, convicted criminals - including convicted terrorists - was their ability to give an indeterminate sentence to protect the public, which was taken away from them by this government.

"That's a concern that I've expressed before.

"What that meant was, in the past, a judge could say: 'This person is so dangerous, he or she can't be released until he can prove to us he's no longer a danger to the public'.

"That's not there now, and that's a concern I've got.

"A second issue is, when people are released on licence, does the Ministry of Justice, does the probation service have the powers and resources to properly supervise people who are clearly dangerous?

"I think these questions will be asked about this individual to make sure we find out what happened here, but also there are wider lessons as well."

The former MP added: "I don't think it's right that someone who is convicted of a serious offence, like what this man is convicted of, should be automatically released."

But, Mr Khan said he was comfortable with the decision to downgrade the UK terror threat level from "severe" to "substantial" earlier this month.

"We've got a fantastic system in our country where politicians don't interfere with the Joint Terrorism Analysis Centre, who do the expert analysis about threat levels arising from international terrorism," he said.