A cop standing at the site of bridge attack in London. Photograph:( AFP )
Convicted terrorist Usman Khan, 28, stabbed to death 25-year-old Jack Merritt and Saskia Jones, 23, in the knife rampage on Friday afternoon, leaving three other people injured.
Britain's Boris Johnson said Sunday he had ordered the security services to step up monitoring of convicted terrorists released early from prison, prompting accusations that he was exploiting the London Bridge attack for political gain less than two weeks before elections.
The prime minister revealed officials were scrutinising around 74 people with terrorist convictions who had been released early from prison-like Usman Khan, who left jail last December and went on to stab two people to death in Friday's rampage.
"They are being properly invigilated to make sure there is no threat," Johnson said.
"We've taken a lot of action as you can imagine in the last 48 hours."
Under the review of released terror convicts, police in the West Midlands said they had arrested a 34-year-old man "on suspicion of preparation of terrorist acts".
British media said he was a former associate of the London Bridge attacker and had been jailed alongside Khan in 2012 over a plot to bomb the London Stock Exchange.
Police said, however, there was no information to suggest a link to Friday's attack.
Khan, 28, was shot dead wearing a fake explosives vest by police on London Bridge after a stabbing spree launched in a nearby hall hosting an ex-offenders' event that also left three people injured.
Police on Sunday formally named the two victims killed as Jack Merritt, 25, from Cambridgeshire in eastern England, and 23-year-old Saskia Jones of Warwickshire in the West Midlands.
PM vows to stiffen sentences
Johnson blamed the previous Labour government for changing the law in 2008 to allow for the early release of prisoners and vowed to introduce minimum 14-year sentences if he regains power in the December 12 vote.
He penned an article setting out the new stance in The Mail on Sunday newspaper, under the headline: "Give me a majority and I'll keep you safe from terror".
Critics hit out at him for appearing to politicise Friday's attack -- including the family of victim Jack Merritt, who said he died "doing what he loved".
While Johnson has vowed to stiffen sentences following the attack, Merritt's family said their son "believed in redemption and rehabilitation, not revenge" and that "he always took the side of the underdog".
"We know Jack would not want this terrible, isolated incident to be used as a pretext by the government for introducing even more draconian sentences on prisoners, or for detaining people in prison for longer than necessary," they said in a statement.
Merritt was a course coordinator at Cambridge University's criminology institute, which was hosting its event by London Bridge to mark five years of its prisoner rehabilitation programme.
Khan, a participant in the initiative during his imprisonment, attended the event armed with two knives, stabbing five people there.
Meanwhile, hospital officials said one of the injured had returned home, while the two others remained hospitalised in a stable condition.
Members of the public have been hailed as heroes for preventing even greater loss of life by tackling Khan -- one armed with a five-foot (1.5-metre) narwhal tusk and another with a fire extinguisher.
The incident came two years after Islamist extremists in a van ploughed into pedestrians on London Bridge before attacking people at random with knives, killing eight people and wounding 48.
After searching on Saturday two properties in central England believed to be linked to Khan, police have said they believe he was acting alone and were not seeking anybody else.
But the Islamic State group has released a statement claiming responsibility for the attack.
Khan, a British national, had been handed an indeterminate sentence for the protection of the public in 2012 of at least eight years in prison.
He was part of an eight-man network inspired by Al-Qaeda which had plotted to bomb targets including the London Stock Exchange, and planned to take part in "terrorist training" in Pakistan.
But his sentence was quashed by the Court of Appeal in 2013 and he received a new 21-year term, comprising a custodial sentence of 16 years and five years on conditional release.
He was then conditionally released from jail around a year ago under so-called licensing conditions after serving about half of his jail term.
Responding to the political furore around the attack, Merritt's father David said: "We don't need knee-jerk reactions."
"It's not lenient policies that are to blame, it's the destruction of the probation service that is supposed to monitor and supervise prisoners after release, & rehabilitation services," he said on Twitter.
That is also the view of the main opposition Labour Party, which noted that the Conservatives have been in power for nearly a decade but had chosen not to tighten the laws around terrorism sentencing.
"I think there has to be an examination of how our prison services work and crucially what happens to them on release from prison," Labour leader Jeremy Corbyn told Sky News.