Stabbings fell in areas targeted by a police crackdown on knife crime, Home Office figures revealed today.
But critics said knife carriers were still being given a "slap on the wrist".
Shadow home secretary Dominic Grieve said anyone caught carrying a knife should face an automatic prison sentence.
Figures from knife crime hotspots revealed the number of youngsters admitted to hospital with stab wounds fell more than a quarter between July and September compared to last year.
The number of serious injuries and deaths against youngsters in the same period fell by nearly a fifth.
In the 10 Tackling Knives Action Programme areas where there was increased use of stop and search, fewer youngsters were caught with knives - down from one in 30 to one in 65.
Mr Grieve said: "We deeply welcome any reduction in knife crime but this has come about because police officers have been focused on the street - something we have long called for.
"However, this has been done through ad hoc, regionally focused operations.
"The government have done this before only to revert to type once they got some good statistics.
"Short term measures will only achieve short term results.
"We need concerted and tough action in the short, medium and long term.
"As well as deploying more police on to every street for good, knife offenders must face an automatic presumption of jail, not a slap on the wrist."
Police carried out 105,000 searches for weapons between June and October and seized 2,200 weapons.
The crackdown followed a string of high profile stabbings of young people during the summer.
In the UK this year, 34 teenagers have died from stab wounds, with 23 of those in London.
The areas are: London, Essex, Lancashire, West Yorkshire, Merseyside, the West Midlands, Greater Manchester, Nottinghamshire, south Wales and Thames Valley.
Home Secretary Jacqui Smith told the BBC: "The forces that we focused on are those where nearly 80 per cent of knife crime actually happens.
"We chose the areas where we were going to make the most difference and we have seen that having an impact.
"But we do want to learn from what's happened in these areas, continue it there and make sure that other forces can benefit from it."