Theresa May has promised a cross-Government response to knife crime after a number of brutal stabbings around the country, including the killing of Connor Brown in Sunderland
The Prime Minister vowed to tackle the causes of knife crime by addressing the issues which led "so many young people" to carry blades.
But Mrs May was accused by political opponents of presiding over reductions in police numbers and cuts to youth services which have contributed to a rise in violent crime.
The Prime Minister, a former home secretary, insisted there was "no direct correlation between certain crimes and police numbers".
"What matters is how we ensure that police are responding to these criminal acts when they take place, that people are brought to justice," she said.
"But what also matters is, as a Government, that we look at the issues which underpin, that underlie, this use of knives and that we act on those.
"That's a cross-Government approach, it's not just about the police, it's about the whole of Government and it's the whole of Government that's responding."
She said "a lot of this is gang-related, some of it will be drugs-related, there are a wide variety of issues that need to be addressed here and that's what the Government is doing".
But Scotland Yard Deputy Assistant Commissioner Graham McNulty indicated that extra officers did make a difference in tackling the problem.
He said: "In advance of the weekend just passed, we had arranged for more officers from our Violent Crime Taskforce to be on duty and we have extended their shifts to raise visibility across London.
"The increased police presence has made a difference, with officers conducting more than 2,500 stop and searches in the last three days alone."
Home Secretary Sajid Javid will chair a meeting of police chiefs on Wednesday, including chief constables from the areas most affected by knife crime.
It comes after the fatal stabbing of 17-year-old Jodie Chesney in an east London park on Friday night in what her family branded a "totally random and unprovoked attack".
On Saturday night, 17-year-old Yousef Ghaleb Makki was stabbed to death in Hale Barns, near Altrincham, in Greater Manchester.
Meanwhile an investigation by Channel 4's Dispatches found the number of recorded offenders aged under 18 committing homicides using a knife or sharp instrument rose by 77% from 2016 to 2018, up from 26 to 46.
Mr Javid said: "Young people are being murdered across the country and it can't go on."
The Home Office said an extra £970 million in police funding is proposed in the funding settlement for 2019-20.
It added that the Offensive Weapons Bill currently before Parliament will introduce new offences to tackle knife crime and acid attacks.
But shadow home secretary Diane Abbott said: "Knife crime is spiralling out of control. There needs to be serious action to save young people's lives.
"This is against a background of huge cuts to youth services and, as senior police officers point out, the surge in school exclusions which leave young people prey to criminal gangs.
"And of course, over 20,000 police officers have been axed by Tory governments since 2010. All of these have contributed to the rise in violent crime, and undermined the police's ability to tackle it."
Police funding has fallen by 19% in real terms since 2010.
Over the same period, officer numbers have decreased by more than 20,000.
At the end of September, there were 122,395 police officers in the 43 forces in England and Wales.
This number was up by nearly 500 compared with 12 months earlier - the first year-on-year increase since 2009.
Liberal Democrat home affairs spokesman Sir Ed Davey said: "There can be no doubt that unnecessary Tory cuts have made our communities less safe."