The attacker has been identified as Usman Khan and was previously jailed for an al-Qaida inspired bomb plot. Scotland Yard is investigating the 28-year-old, who was known to the authorities and fitted with an electronic tag to monitor his movements. He was allowed out a year ago after serving time for his part in a plot to blow up the London Stock Exchange.

Khan was arrested in December 2010 and released on licence (parole) in December 2018, wearing an electronic tag.

A police search believed to be linked to the London Bridge investigation is being carried out in the West Midlands at a three-storey block of flats in Wolverhampton Road, Stafford, close to the town centre.

Two people, one man and one woman, died after being stabbed in the attack that started at Fishmongers’ Hall during a conference about rehabilitating offenders. Another two women and a man were injured and taken to hospital.

The suspect was shot dead by police on London Bridge, about 2pm.

Khan was attending the conference, according to the Met police assistant commissioner, Neil Basu. He said: “We believe that the attack began inside before he left the building and proceeded onto London Bridge.”

The Parole Board has issued a statement saying it had no involvement in the release of Khan.

Footage has emerged showing three members of the public, including one armed with a fire extinguisher and another with a five-foot narwhal tusk, grappling and grounding the attacker before police arrived.

The mayor of London, Sadiq Khan, has argued that more resourcing is needed for the police, saying “you can’t disaggregate terrorism and security from cuts made to resources of the police, of probation, the tools that judges have.”

Sadiq Khan said there would be an increased police presence on the streets in the wake of the attack to reassure members of the public.