Children as young as 11 are carrying knives because they fear being attacked, according to a report.
Children carry knives out of fear
Youngsters told researchers they turned to gangs for protection because their parents and teachers did not defend them. And they said tougher prison sentences would not deter them from carrying a blade.
But they revealed that the impression among teenagers who carry knives is that, if caught, they are more likely to be given an electronic tag than jailed.
One boy told researchers: "He wouldn't be thinking about six years (in prison). He's probably thinking he's going to be six foot (sic) deep if he don't carry one."
The report included interviews with a group of under-18s jailed at Feltham Young Offenders' Institution or expelled from school.
The author of Why Carry A Weapon, Nicola Marfleet, a governor at Pentonville Prison, said harsher penalties for knife carriers would have a "limited" impact.
She said: "The young people I interviewed spoke about their 'enemies' who all carried knives and about how they were always anticipating attack, living under a constant fear of reprisal from other gangs who were armed and therefore they also needed to be.
"Several young people spoke honestly about their desire to live in a world where they didn't need to carry a knife, but most felt that it had 'gone too far now' and that there was nothing really that could be done to turn back the tide of knife crime."
Knife crime has blighted the capital, with 27 teenagers killed in London this year alone.
The Howard League for Penal Reform, which was publishing the report, called for "lasting solutions" to knife crime problems.Director Frances Crook called for targeted health, education and youth community projects.