Giving police more stop-and-search powers is a “recipe for unrest” Labour have warned.
Boris Johnson has lifted restrictions on the practice in order to “come down hard” on crime stop-and-search powers.
The new PM has also called for tougher sentences for violent criminals.
But Labour have warned that extending Section 60 stop and search powers over the summer is a “tried and tested recipe for unrest, not violence reduction”.
Shadow Home Secretary Diane Abbott said “random stops have only poisoned police community relations.”
When Mr Johnson was Mayor of London the fatal shooting of a black man in Tottenham by police who believed he had a gun, led to rioting in the city which spread across the country.
After the inquest into Mark Duggan’s death ruled that he was “lawfully killed”, the then Home Secretary Theresa May called for a change in the way stop and search was used.
But despite the change in the rules in 2014, racial disproportionality has worsened and black people are now eight times more likely to be stopped than whites.
While the Liberal Democrats said that the new PM was intent on repeating the “failed policies of the past”.
Under the Government’s plans, an existing pilot project, which allows police to deploy stop-and-search powers in an area without the authorisation of a senior officer, will be extended to cover an additional 8,000 officers in England and Wales.
Mr Johnson acknowledged the move would be controversial but said he believed it would have the backing of the parents of those children most at risk of getting caught up in knife crime.
“We are making clear that the police can and should make use of their stop-and-search powers,” he wrote.
“I know that left-wing criminologists will object. And, of course, it is right that stop-and-search should be done courteously and in accordance with the law.
“But I also know that the people who back this intervention most fervently are often the parents of the kids who are so tragically foolish as to go out on the streets equipped with a knife, endangering not only the lives of others but their own.”
The Prime Minister said he was determined to tackle rising levels of knife crime amid the impression of a growing “culture of insolence” among “thugs” who believed they could act with impunity.
He said the Government would be investing £2.5 billion in creating 10,000 new prison places to ensure serious violent and sexual offenders got the sentence they deserved.
Since taking office last month, Mr Johnson has already set out plans to recruit another 20,000 police officers over the next three years.
His latest announcement will be seen as further evidence that he is preparing the ground for an autumn general election amid continuing deadlock in Parliament over Brexit .
It comes just days after a police officer received multiple stab wounds after being attacked with a machete in east London.
Writing in The Mail on Sunday, the Prime Minister said the “first duty” of any government was to protect the public.
“We have the impression of a growing culture of insolence on the part of the thugs; and in the face of that sense of impunity – entirely misplaced – I believe the British public knows instinctively what we must do,” he said.
“We need to come down hard on crime. That means coming down hard on criminals. We need to reverse the balance of fear. I want the criminals to be afraid – not the public.”
The Prime Minister said the investment in the prison system – approved by Chancellor Sajid Javid – was “long overdue”.
When police did catch violent criminals, he said that it was “vital they get the sentence they deserve”.
He wrote: “In the past five years, we have seen literally hundreds of convicted rapists who have come out of prison commit another sexual offence.
“This cannot go on. I am afraid that as a society we have no choice but to insist on tougher sentencing laws for serious sexual and violent offenders, and for those who carry knives.
“Our first duty is to protect the public in the most basic way – and that means taking such people off the streets.”
Ms Abbott said: “This draconian approach shows that Boris Johnson ’s government has no real plans to invest in policing or a public health approach to tackling violent crime. They have opted to ‘appear tough’ instead of dealing with the root causes of crime.
“Evidence based stop and search will always be a vital tool in preventing crime. But random stops have only poisoned police community relations.”
The Liberal Democrats Home Affairs spokesperson Ed Davey said: “Boris Johnson isn’t tough on crime – or tough on the causes of crime.
“Far too many young lives are being destroyed by an epidemic of serious violence, and Johnson doesn’t have any answers.
“He just wants to repeat the failed policies of the past.
“This announcement today will not make our streets safer.
“He tried a big increase in suspicion-less Stop & Search when he was Mayor of London, but his own Government’s analysis shows it didn’t work to cut crime.
“All it does is disproportionately affect BAME communities and undermine the very community policing we need to stop young people carrying knives.
“The Tories already tried introducing tougher prison sentences for knife crime, and knife crime has soared. The UK already imprisons more people than any other country in Western Europe.
“Instead of wasting money locking more people up, the Government should be investing in the things that prevent crime, like community policing and youth services.”