A member of ministerial advisory group on youth offending says violent youth crime is on the rise because more young people are carrying weapons.
A Justice Ministry report, looking at child and youth offending from 1992 to 2007, shows police apprehension rates in 2006 and 2007 were the lowest since 1995.
But the statistics also show violence apprehensions for children and young people increased between 1995 and 2007.
John Langley, from the Ministerial Independent Advisory Group on Youth Offending, says the increase in grievous and serious assaults committed by young people is partly due to the availability of drugs and alcohol, but also because more young people are carrying weapons, such as knives and screwdrivers.
He says police need greater powers so they can identify and remove weapons from young people in public places.