British Prime Minister Boris Johnson talks with political commentator Andrew Marr during BBC's Andrew Marr Show on Sunday in London. Photo: AFP

 

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 scrutinizing around 74 people with terrorist convictions who had been released early from prison like Usman Khan, who left jail in December last year 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 told the BBC.

"We've taken a lot of action as you can imagine in the last 48 hours."

Johnson and the head of the opposition Labour Party, Jeremy Corbyn, attended a vigil on Monday for the two victims.

The vigil was held in Guildhall Yard, in the heart of the City of London, to honor Jack Merritt, 25, and Saskia Jones, 23, as well as the injured, the emergency services and members of the public who tackled the attacker.

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.

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 politicize 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.