Rory Stewart will boost spending on armed police to tackle terrorism if he is elected Mayor of London.
The former Conservative minister said he would recruit more local police with knowledge of Islam to address radicalisation at a community level.
It comes after a terrorist who pledged allegiance to Islamic State stabbed two people on Streatham High Road on Sunday.
Mr Stewart also said he wants to take control of London probation services – currently the remit of central government rather than the Mayor.
He wants more terrorist separation units in London prisons, and backs interventions from Imams to deradicalise convicted offenders.
His said his approach builds on his work as Prisons Minister in the Conservative government, and would ensure that “terrorists don’t fall through the gaps in the current system”.
Mr Stewart said: “I would also increase investment in the police’s armed rapid response capacity.
“We learned the value of such teams in the Charlie Hebdo terrorist attacks in Paris, and it was the investment in these teams that allowed the police to act so quickly in Streatham on Sunday afternoon.”
His plan is backed by General Sir Graeme Lamb, who led counter-insurgency in Iraq and Afghanistan.
Sir Graeme said Mr Stewart’s approach is “sober, and realistic, rooted in experience”.
He said: “Tackling terrorism requires deep understanding and a willingness to wrestle with complex causes and cultures.
“It needs energy, patience and attention to detail.
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“Rory Stewart’s greatest strength has been his ability to sit down and listen.”
But a London Labour spokesperson accused Mr Stewart of “selective amnesia”.
He said: “Rory was Prisons Minister when the government was warned about the threat posed to Londoners by terrorists facing release.
“He was also part of the Tory government whose cuts have led the country to this current terrible state of affairs.”
He added: “In stark contrast, Sadiq Khan is standing up for Londoners – with a plan to keep London safe by being tough on crime and tough on the causes of crime.”
Liberal Democrat candidate Siobhan Benita agreed it was “hard to ignore” Mr Stewart’s role in a government that cut prison funding, police numbers, rehabilitation and youth services.
She said: “The bottom line is that people shouldn’t come out of prison more dangerous than when they go in.
“The Conservative government must transform prisons into places of rehabilitation by ending overcrowding and improving provision of deradicalisation programmes and other rehabilitation services.”
Ms Benita said she’d put police “back at the heart of our communities” by reopening police stations and recruiting local officers.
Green candidate Sian Berry – who is also co-leader of the national party – said the Streatham attack must not “divide our communities”.
She said: “Questions need to be asked about the attacker’s early release from prison as well as the on the debilitating effects that privatisation has had on the prison and probation services, and the quality of rehabilitation offered to prisoners.
“It is time to reinvest in those services and build a system in which rehabilitation works, to make everyone safer.”
Conservative candidate Shaun Bailey was approached for comment.