The number of crimes related to knives and other offensive weapons dealt with by the courts reached its highest level for nine years last year, figures show.
The Ministry of Justice says 21,484 offences were dealt with in England and Wales in 2018 – the highest number since 2009 (25,103).
Of all those convicted or cautioned last year, 21% were under 18.
The figures show 37% of all offences led to an immediate jail sentence.
In 2009, 23% of offences ended up with jail. Cautions and fines were twice as likely to be used, compared with 2018.
The proportion of offences which resulted in just a caution was 23% (5,817) in 2009 and 11% (2,410) in 2018.
Fines were issued in 4% (951) of these offences in 2009, compared with 2% (524) in 2018.
The MoJ said the average length of custodial sentences classed as “immediate” – therefore not including suspended sentences – was 8.1 months last year. That is the longest average term since comparable records began in 2008.
The annual figures have been published following a spate of fatal stabbings, including the killings of three 17-year-olds in less than a week earlier this month.
And it is a day after police have been promised an extra £100m by the government to help them tackle a knife crime in England and Wales.
The government has said offenders are now more likely to go to jail for knife or offensive weapons crimes.
Justice Minister Rory Stewart said: “Knife crime destroys lives and shatters communities, and this government is doing everything in its power to tackle its devastating consequences.
“Sentences for those carrying knives are getting tougher – they are more likely to be sent straight to prison – and for longer – than at any time in the last decade.”
Responding to the figures, Labour’s Shadow Home Secretary Diane Abbott said: “Surely the Tories don’t need any further evidence that not enough is being done to tackle knife crime?”
She called on the government to “stop talking” about its approach to fighting knife crime and said it should instead “properly” fund the police and youth services.
The MoJ figures – which cover not just knives, but other offensive weapons such as deliberately broken bottles, sharpened screwdrivers, knuckle dusters and corrosive liquids – only relate to England and Wales.
In Scotland, which has a separate legal system, the number of offences of handling offensive weapons recorded by Police Scotland between April and September 2017 was 4,060 – nearly double the figure measured for the same period four years earlier.
A separate report by the Scottish government last year said the proportion of convictions resulting in a custodial sentence had “generally fluctuated” between 30% and 40% between 2007-08 and 2016-17.
In Northern Ireland, the number of offences of handling offensive weapons recorded by Police Service Northern Ireland between February 2017 and February 2018 was 970 – a rise of 9% on the previous year’s figures.
A separate government report published last year said 20% of all convictions in Northern Ireland in 2017 that were related to possession of weapons resulted in imprisonment.