Teenagers who commit antisocial offences such as graffiti, theft and possession of knives or liquor could have their movements and right to associate with other people, such as gang members or co-offenders, limited under the State Government's new Youth Conduct Orders.

They also could be forced to meet school attendance requirements, complete drug and alcohol programs and deal with mental health issues.

Attorney-General John Hatzistergos said the orders would help tackle youth crime and reduce reoffending.

However, the scheme will not apply to the Illawarra, where youth vandalism has been occurring on a weekly basis.

The Illawarra Mercury has been highlighting the problem of vandalism and graffiti in its Halt the Hoons campaign.

Mr Hatzistergos said the orders would be trialled in Armidale, Campbelltown and Mt Druitt from Wednesday.

A spokesman for Mr Hatzistergos could not explain how the Government chose where the trials would be conducted but said the decision was made in consultation with police.

He said if the two-year trials were successful, the Government would consider rolling out the scheme in the Illawarra.

"This is a tough new approach to tackling youth crime and getting young people to face up to their antisocial behaviour before they embark on a life of crime," Mr Hatzistergos said.

"The scheme zeros in on the underlying causes of antisocial behaviour in youths' family and school lives to try to divert them from spiralling into a life of crime."

Opposition Attorney-General Greg Smith said the Government had taken too long to introduce the scheme, which was passed by Parliament in November, last year.

"The delay in putting these laws into practice has resulted in the state's juvenile detention centres overflowing," Mr Smith said.

"Unfortunately we have seen a number of young people held in detention on remand awaiting trial, only to be released when their matter is heard by a magistrate or judge.

"It is these young people who should not be in juvenile detention centres that will benefit."