Former Brexit Party MEP Ben Habib said London’s Mayor would be better off accepting the need for police to use stop-and-search tactics – something he actively disapproved of prior to his election in 2016. Meanwhile, the scale of the crisis was underlined yesterday after the fatal stabbing of a 15-year-old boy in Hayes in west London. As well as the incident in Hayes on Thursday, there were also three other stabbings on the same day, one near Clapham, one in Harrow and one in Streatham.

On Thursday Mr Khan shared footage of him during a walkaround with officers from the Met’s Violent Crime Task Force.

At one point police gave chase to suspects fleeing a local park, subsequently arresting them and recovering what appeared to be a large quantity of cannabis.

Mr Habib claimed: “Sadiq put a stop to ‘stop and search’ when he became mayor. That is why violent crime went through the roof during his tenure.

“It is ironic that the video he posted on Twitter involved effectively a stop and search – the policemen stopped the youths only because they moved away in haste.”

Mr Habib added: “The police were not aware of any crime being committed.

Mr Khan spoke out against stop-and-search in 2015 during his first Mayoral campaign, saying: “The last few years have shown what can be achieved when there’s a concerted effort to reduce the overuse of stop and search.

“But there’s still much more to be done, and if I’m Mayor I’ll do all in my power to further cut its use. Overuse of stop and search can have a dramatic effect on communities.

“It undermines public confidence in our police if Londoners are being stopped and searched for no good reason.”

However, three years later, after a spate of knife attacks, he changed tack, committing the Metropolitan Police would be “ramping up its fight against violent crime”.

He added: “This will include a significant increase in the use of targeted stop and search by the police across our city.

He added: “This will include a significant increase in the use of targeted stop and search by the police across our city.

“I know from personal experience that when done badly, stop and search can cause community tensions.

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“But when based on real intelligence, geographically focused and performed professionally, it is a vital tool for the police to keep our communities safe.”

In the video posted this week, Mr Khan says: “Keeping Londoners safe is my top priority.

“I am going to be going out tonight with the Violent Crimes Task Force, that is funded by City Hall, to see for myself the work they are doing to try to keep Londoners as safe as possible.

“I’m determined to use all the powers and resources I have to be both tough on crime, and tough on the causes of crime as well.”

The teenager died after being stabbed multiple times yesterday morning.

Police were called to reports of a fight on Blyth Road in Hayes just before 8.35am on Friday, and despite the efforts of paramedics, the youngster died at the scene.

The incident happened close to Global Academy – a college for students aged 14 to 19 – at a time when youngsters would have been making their way to school.

The Metropolitan Police said a suspect had been detained, but provided no further details.

Tia Rek-Williams, 21, a teacher who lives nearby, said the incident had been “traumatising”.

She said: “I didn’t see the initial stabbing but I did see past the point where the boy was on the ground.

”They were saying ‘come on, you’ve just got 30 seconds, hold on, keep fighting’ and as they were saying that I saw his hand drop and his eyes close. It was so traumatising.”

Ms Rek-Williams said emergency services had arrived around 30 seconds later and the boy had been treated with a defibrillator.

She added about six people had tried to help the boy while neighbours came out of their houses and gathered in the road.

She added: “It happened in broad daylight, a 15-year-old boy, there are so many cameras. It just shows you nothing can stop these people doing these things.

“This happened literally in the middle of the street, not down a back alley, in front of people’s houses. It’s just awful.”

Police commander for Hillingdon, Chief Superintendent Peter Gardner, said: “I am deeply saddened to hear of the tragic loss of a child’s life to knife crime in Hillingdon.

“This incident, that claimed the life of a 15-year-old boy, took place during this morning’s school run.

“A family has been devastated and the effects of this terrible incident will reverberate throughout our communities.

“As a parent of a teenage boy myself, I cannot imagine the pain the family is going through and I offer our full condolences and support.

“Police patrols today and throughout the weekend have been enhanced in order to provide a more visible and reassuring presence for the public. If you have concerns please do approach my officers and speak with them.

“Local officers will support our homicide detective colleagues and I thank the public for their patience as officers deal with the crime scene and local enquiries.

“We work tirelessly with our borough partners and communities to challenge violent crime and to stop the loss of young lives to knife crime.

“More widely, across London in the coming months, a large scale operation will run throughout the summer to challenge and suppress violent behaviour, but we need the help of parents, carers and anyone with information about those carrying knives to come forward.

“A homicide investigation will be launched following this morning’s tragic incident. Please work with us to prevent further young deaths by sharing what you know.”

The attack is the latest this month, with others having occurred in Streatham, Clapham, Islington and Plumstead.

Express.co.uk has contacted Mr Khan’s office to offer him a chance to comment.

Four knife attacks in less than 24 hours:

• A man in his early 20s was taken to hospital with knife wounds after emergency services were called to the scene of an attack in Leathsail Road, South Harrow at 2.15pm on Thursday
• Less than half an hour later, a man was hospitalised with multiple stab wounds after an attack in Cedars Road in south London. Two men fled the scene in a car, which was then involved in a collision, at which point they escaped on foot
• At 4pm, in Streatham, also in south London, a youth thought be in his late teens was found with a knife wound to the chest. Tragically, he died in hospital later the same day, with four men and three women subsequently arrested on suspicion of various offences
• Finally, a 15-year-old was also killed after being stabbed in Blyth Road, Hayes yesterday at 8.34am