Retailers will be required to report any bulk or suspicious-looking purchases of knives on their platforms to police to prevent illegal resales happening across social media accounts.

The government will also increase the sentence for selling weapons to under 18s from six months to up to two years prison time, which could apply to an individual who has processed the sale or a chief executive of the company.

This increased penalty will also apply to the sale or supply of prohibited offensive weapons such as recently banned zombie-style knives, following police evidence outlined by Commander Stephen Clayman, the National Police Chiefs' Council lead for knife crime, where he identified a discrepancy in current legislation which means there is more leniency for illegally selling weapons than possessing one.

In recognition of the broad array of knives - legal or banned - that are involved in knife attacks, a new offence of possessing an offensive weapon with intent for violence will be introduced in the Crime and Policing Bill which will come with a prison sentence of up to four years in prison. This means that no matter if the weapon in possession is legal or not, if there is intent to cause violence, it is a crime.

Home secretary, Yvette Cooper, said: ‘It is horrifying how easy it is for young people to get hold of knives online even though children's lives are being lost, and families and communities are left devastated as a result.

‘Not enough has been done to tackle the online market over recent years which is why we made it an urgent priority in our manifesto and the measures today will be underpinned by investment for a new dedicated police unit to go after those who are breaking the law and putting children and teenagers lives at risk.'

She added: ‘This government has set an ambitious mission for the country to halve knife crime over the next decade and we will pursue every possible avenue to save young lives.'

The new measures will collectively be known as ‘Ronan's Law' in honour of Ronan Kanda who was killed in 2022 in a case of mistaken identity near his home in Wolverhampton aged 16. His killers, who were also teenagers, illegally bought lethal weapons online and collected them from a post office on the day of the attack, with no age or identity verification taking place.

In the spring, the Home Office intends to launch a consultation into a registration scheme for retailers in order to sell knives online.

The government has an ambitious mission to halve knife crime over the next decade and tackling the online space is a core part of that plan.

Graham Wynn, assistant director of regulatory affairs at the British Retail Consortium, said: ‘Retailers take their responsibilities seriously and are fully committed to playing their part in making sure knives don't make their way into the wrong hands.

'We look forward to considering the full details of the new proposal and welcome the commitment from the Home Office to meet retailers on this vital issue to ensure the safe sale of knives.'