Sadiq Khan has attacked the Government over being “weak on the causes of crime” and suggested that cuts could be driving rising violence.

Speaking after four young men were murdered in unrelated stabbings in the capital during New Year’s Eve celebrations, the Mayor said police were already doing everything in their power.

“The police are being tough on crime, but the Government are being desperately weak on the causes of crime,” he added.

“Getting back to being ‘tough on the causes of crime’ will require a massive investment in the services that have been neglected for too long, tragically letting our young people down.”

Critics have hit out at Mr Khan for presiding over rising violence in London since he was elected mayor in 2016, having vowed to “challenge gang culture and knife crime head on” in his manifesto.

The number of teenagers murdered in 2017 was the highest since 2008 and there is mounting public concern over the number of stabbings and a spike in acid attacks and moped robberies.

Violent offences have risen by 19 per cent in England and Wales in the past year, and by 3 per cent in London.

Scene where woman was found dead in Finsbury Park

Mr Khan claimed real-terms funding cuts to youth services, community groups, education, probation and the police since the 2010 general election had “reversed decades of progress in tackling the root causes of violent offending”.

He also hit out at the “botched” partial privatisation of probation services, the ongoing prisons crisis and “scandalous” reoffending rates.

The Labour Mayor called on ministers to prioritise youth services, community work, mental health, probation and prisons to fight the causes of crime.

“On this Government’s watch, these critical services have been allowed to deteriorate and starved of funding and we are now paying a heavy price,” Mr Khan said.

“I am doing everything I can to tackle this scourge in our communities. Keeping the country safe should be the Government’s priority too, and it is time ministers stopped shirking this responsibility.”

Scotland Yard appealed for the public’s help combating knife culture after the four New Year’s Eve murders, which have been followed by another stabbing in Harrow and a murder in Ilford.

Sir Craig Mackey, the Deputy Commissioner of the Metropolitan Police, said it was “truly unusual and extraordinary” for so many murders to take place in such a short period of time.

“There are a number of issues affecting knife crime,” he added. “We are doing our part... but we need others working with us to help tackle those underlying issues around a knife culture that has emerged across London.”

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City Hall claimed that reductions to the central Government funding given to councils has triggered more than £22m of cuts to youth services since 2011, seeing 30 youth centres closed.

It said London’s schools “face £99m in real terms cuts in 2018-19 alone”, with the funding gap for children’s services predicted to reach £2bn by 2020.

The figures could not immediately be verified by The Independent and the Home Office has not yet replied to a request for comment.

Mr Khan’s office said mental health services were also “chronically underfunded”, leaving young people with behavioural problems in later life, and that the proportion of young male convicts returning to crime had risen to almost 40 per cent in London.

The capital’s probation services have been partly handed to one of several private “Community Rehabilitation Companies”, which were heavily criticised in a recent watchdog report accusing them of putting the public at risk.

Senior police officers previously said they were being used as the “service of last resort” for shrinking public services, particularly in mental health, while calling for more funding to tackle rising crime and terrorism.

Sophie Linden, London’s deputy mayor for policing and crime, said the Met was in a “very difficult position” after officer numbers were cut to 30,000 in the capital.

“My concerns, and I’ve been given assurances that it is possible to police London at those numbers, if they go below 30,000, which is exactly what the budget trajectory looks like, that is going to put the safety of Londoners at risk,” she told the London Assembly budget and performance committee on Thursday.

“30,000 officers, we can cope with it, but it is not ideal in any sense because we know demand is rising, the population of Londoners is rising, the young population of London is rising and that comes with its complexities, opportunities as well, but great challenges in terms of policing. It is a real worry.”

She added: “London is not in a good position, it is in no way a better position [than previously], it is in a very, very difficult position, and that is about safety.”

Sir Mackey said cuts were forcing the Met to be more “prescriptive”.

“We are having to make really, really difficult choices in terms of what we can prioritise and what we can do,” he said.

“What you're seeing is increasing prioritisation of workloads... having to be really, really clear when we take something on or try something new about what gives.”

A Home Office funding settlement announced last month was heavily criticised for relying on elected Police and Crime Commissioners taking more money from council tax to fund forces.

The Metropolitan Police has already released guidelines instructing officers to stop investigating some “low-level crimes” as it works to save £400m by 2020 and other forces are believed to be considering similar policies amid a falling number of police officers.

A recent report by HM Inspectorate of Constabulary warned that police forces are failing to respond to low-priority crimes because of “significant stress” caused by continued budget cuts amid a huge rise in demand.

A Government spokesperson said: “Violent crime has devastating consequences on our communities and we are determined to tackle this head on.

“The Metropolitan Police will receive more than £2.5billion in funding and also has £240m of reserves to draw from. The Mayor of London is accountable to the public for Met’s performance and is empowered to raise local precept to increase funding.