Graphic images of real injuries inflicted by knives feature in a new £3m government advertising campaign against youth violence.
The ads devised by teenagers aim to show the dangers of carrying a knife.
One shows a man with a knife and a screwdriver in his chest, and deep, gaping wounds to the body.
Meanwhile, Metropolitan Police chief Sir Ian Blair said nearly 200 weapons had been seized as operations against knife crime in London were stepped up.
Speaking at a news conference on the day the government launched its advert campaign, Sir Ian Blair said: "To parents it is tough love time. In addition to conversations about drink, drugs and relationships there are now conversations about knives."
The Home Office said it wanted children who carry knives to see what could happen if a weapon was turned on them.
It should be remembered that you are more likely to be a victim of knife crime by carrying a knife, rather than a knife protecting you
Alf Hitchcock Association of Chief Police Officers
Minister Vernon Coaker said that the new adverts' message was conveyed by young people the same age as would-be victims to maximise their impact.
He added: "We know that many young people carry a knife because they are fearful and these adverts tell powerful stories about the dangers of going down that path.
"People have got to get the message that if they carry a knife, there's more chance of it being used against them."
The campaign is being launched after a spate of stabbings of young people. Most recently, 18-year-old Rob Knox was murdered outside a pub in Sidcup, south-east London.
Social networking sites
The first phase of the three-year campaign will feature newspaper and radio adverts, as well as two "viral" internet videos.
Viral advert of a knife stabbing
The first features the shocking images, taken from a medical photo library, as slides in a fictional medical lecture given by a surgeon who has to deal with such injuries.
A second viral shows CCTV footage - performed by actors - of a knife stabbing on a shopping street.
Both adverts will be distributed to young people through social networking websites such as Bebo and on mobile phones.
Campaigners will also hand out postcards showing a hand mutilated by a knife attack to young people on the street.
Eighteen teenagers from England and Wales took part in a summit in April and came up with the idea of using injuries to deter their peers from carrying knives.
One of those involved, Khadijah Murchison, 18, from Bristol, said: "All the young people that went to the creative summit have been affected by knife crime, so to share our experiences with each other and come up with ideas and adverts that will help reduce knife crime was great.
"Hopefully, it will make a real difference."
The campaign will run alongside a series of adverts aimed at mothers, encouraging them to talk to their children about knives.
The Met Police commissioner said young people were now likely to face a custodial sentence if they were caught with a knife.
The adverts use the images to illustrate a fictional medical lecture
"You are now more likely to stopped and searched," he warned.
"If you are carrying a knife, you will be arrested and you are likely to be prosecuted."
He added that police in the capital had stepped up operations against knife crime, carrying out 4,277 stops and searches during the previous four weeks, seizing nearly 200 weapons and arresting 210 people.
London's deputy Mayor for policing, Kit Malthouse, said: "Every one of these 200 weapons represents a tragedy averted."
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