The Islamic State terror group has claimed responsibility for the knife-attack in central London where a convicted terrorist killed two people before being shot dead by police.
The group via its propaganda Amaq news agency said on Saturday that the attack was carried out by "a fighter from the Islamic State", according to the Site Intelligence Group, which monitors jihadist activities.
"The person who carried out the London attack... Was a fighter from the Islamic State, and did so in response to calls to target citizens of coalition countries," the IS statement read.
However, it did not provide any evidence to support its claim.
The attacker, identified as Usman Khan, was a convicted terrorist who was jailed seven years ago over a plot to bomb the London Stock Exchange and build a terrorist training camp on land owned by his family in Pakistan-occupied Kashmir.
Khan had also discussed staging a Mumbai-style attack on the UK Parliament and described by the judge who sentenced him for terrorism offences in 2012 as an ongoing risk to the public with a "serious, long term venture in terrorism".
He went on a rampage on Friday and killed one man and a woman and injured three others before being shot by armed police officers.
"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," Scotland Yard's Head of Counter Terrorism Policing Assistant Commissioner Neil Basu said on Saturday.
The profile of Khan dating back to his conviction in 2012 reveals his links with terror groups. He had been secretly recorded talking about plans to recruit UK radicals to train at a camp in Pakistan-occupied Kashmir (PoK), the region his family comes from.
He and two other co-conspirators had conducted a surveillance trip around central London as they talked about launching a Mumbai-style attack on UK Parliament. 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.
Khan had originally received an indeterminate sentence to be kept behind bars for public protection but this was quashed by the UK Court of Appeal in April 2013, after which he was given a determinate 16-year jail term and ordered to serve at least eight years in prison before being considered for parole.
He had been released on licence, or parole, in December last year and was reportedly being monitored via an electronic tag.
UK home secretary Priti Patel, who had recently unveiled plans for tougher sentences for violent criminals, said the police needed "space and time" to complete the investigation and that it was not right to "speculate".
"We're supporting the police through this very difficult investigation. I think it's fair to say we're all shocked and saddened," the minister said.
The Metropolitan Police said Khan attended a conference on prisoner rehabilitation organised by the University of Cambridge associated Learning Together organisation at Fishmongers' Hall in London Bridge earlier on Friday afternoon.
He is thought to have participated in the morning session, taking part in various workshops, in which he described his experiences as a prisoner, before going on a knife rampage and threatening to blow up the building when police were called to the scene.
It later emerged that Khan had been wearing a hoax suicide bomb vest after he was over-powered by members of the public before being shot by police gunmen.