Drugs such as P may be the cause of a dramatic increase in the number of teen violence crimes, Justice Minister Mark Burton says.
On Monday, in the Ministry of Justice first annual report on youth offending, statistics showed that from 1992-2006 police apprehensions of people aged 14-16 were steady at around 30,000 annually.
The percentage of violent offences had risen dramatically, from 2690 in 1995 to 3743 in 2006.
"While the overall trend is in the right direction, it is a worrying trend, that mirrors the wider population, in terms of that increase in violent offending," Mr Burton said.
"I think there is a lot more work required in terms of what sits behind that. Obviously there is speculation about the impact of P and the growth in the use of those sorts of substances, and of course it is a matter of concern."
The Government in 2002 set up three groups to co ordinate prevention of youth crime, and established 32 local teams and two programmes for serious offenders.
Mr Burton said the Government had to be careful analysis of the cause was correct to make sure prevention programmes had any impact.
"It is important that the efficacy of those programmes is constantly monitored, but I think the indications are that there is some good positive work being done ... but I don't think we can expect instant transformation or a silver bullet to what I think are complex and diverse causal effects."
National Associate Welfare spokeswoman Anne Tolley said the figures showed Government promises were all talk and no action.
"It's critical we get serious about youth offending. No amount of head- shaking and hand-wringing will put the brakes on," Mrs Tolley said.
"The Labour Government needs to admit it has allowed the problem to spiral out of control and that the youth justice system is failing."
Maori Party co-leader Pita Sharples said the findings needed to be carefully analysed to avoid "demonising" Maori. While not shying away from what he called atrocious Maori youth offending figures - 47 per cent of 14-16-year-olds apprehended last year were Maori - Dr Sharples said the percentage apprehended had dropped between 1995 and 2002.
New Zealand First law and order spokesman Ron Mark said almost half of police apprehensions were people aged between 10 and 20 years.