Boris Johnson has condemned the early release of criminals after it emerged that the man who carried out the latest London Bridge terror attack was a convicted Islamist who had been freed from prison on an electronic tag.

Two people were murdered and at least three more seriously injured when the suspected jihadist, wearing a fake suicide vest, went on a rampage at a criminal justice seminar he was attending.

Police named the man as Usman Khan, a 28-year-old from Staffordshire. Neil Basu, the Metropolitan Police's assistant commissioner, said his team were carrying out searches at the suspect's residence but believe that he was acting alone.

The Prime Minister paid tribute to the extraordinary bravery of members of the public and the emergency services who helped tackle the maniac, describing them as “the very best of our country”.

But he also said he had "long argued" it was a "mistake to allow serious and violent criminals to come out of prison early”.

He added: “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."