Key Points:

The worst of the worst young criminals could find themselves forced to wear electronic tracking devices to school, while others could be sent to military-style boot camps.

The initiatives - announced yesterday - are part of a raft of Government measures designed to crack down on underage offenders.

Other initiatives include the doubling of Youth Court residential sentences to a maximum six months, and a widening of the court's jurisdiction, to include 12- and 13-year-olds.

The Government says about 25 youth offenders will be electronically monitored, while 40 - males and females - will go through the boot camps each year.

Another 175 will do other programmes run by providers, which the Government will insist have a military component.

Prime Minister John Key said one problem with youth offenders was disengagement from school, so if intensive monitoring with an electronic bracelet saw them back in class it was a "positive thing".

"They [bracelets] are not very intrusive in nature. As I understand it, they are an ankle bracelet so you don't necessarily see them," he said.

The monitoring will be part of "spotlight sentences" aimed at those who repeatedly breach curfews or other conditions. It will be carried out by a private contractor such as Chubb, which is currently responsible for home detention.

Secondary Schools Association president Peter Gall said the Government would have to carefully consider the implications of electronically monitoring school-aged criminals.

"A lot of thought needs to go into it. There could be discrimination against a student either way. They might wear the bracelet as a status symbol, and attract attention for their notoriety.

"Or they might face pressure from students because they are identified as a criminal."

The boot camps will run for three months, with 10 offenders in each intake, and will be followed by nine months of support and mentoring.

The Defence Force will help develop the camps, although the Government could not say who will run them, what the regime might entail or where they would be based.

Judges will decide who goes to the camps, but the Government wants it aimed at those on their "last chance" with the court.

Labour attacked the boot camps as having previously been found to have a 92 per cent reoffending rate and producing "better, faster criminals".

Mr Key said he accepted that boot camps could be unsuccessful when in isolation and for a short time, "but we don't accept it when it's part of a more comprehensive approach".

The legislation - estimated to cost $35 million a year - will be introduced to Parliament this week, but Social Development Minister Paula Bennett said the boot camps would not be operational until after April next year.

Ms Bennett said there were safety considerations, as "it's not like you can just go down to an army camp and set it up".

Youth Court residential sentences will be a next-tier punishment, below boot camp.

The Government believes all young offenders will be able to be kept in custody or on programmes.

A 30-bed youth justice facility is due to be completed in Rotorua, and 10 more beds are to be added at the Palmerston North unit, creating a total of 150 youth custody places by December.

The Government says it will raise the yearly places on supervision with activity programmes from 125 to 175 to accommodate the new orders.

It is these programmes that will require a military-style component.

Mr Key made a big play of boot camps in his state of the nation speech last year, and the "1000 ticking time bombs" of youth offenders on the streets.

Asked if 40 young people on boot camps a year was a small number, Mr Key said the next tier of programmes meant military-style discipline would reach "hundreds".

Other initiatives include compulsory parenting education orders.

- ADDITIONAL REPORTING: Isaac Davison