The Public Service Association's general secretary Stewart Little said not a day goes by when there isn't some kind of violent incident across the state in juvenile justice centres.

"NSW's juvenile justice system is in crisis because of chronic under-investment by the state government. Even as the number of young offenders declines, the rate of violence in centres is rising," he said.

"The lack of investment in juvenile justice is hugely frustrating for our members. No one should go to work worrying that they may not make it home safely at the end of their shift."

During six months in 2018, there were more than 70 reported assaults across the NSW system - which houses about 280 offenders. At the Riverina Juvenile Justice Centre in 2019, the PSA stated there's been at least three assaults, issues of contraband and incidents of detainees on the roof.

On Wednesday, police attended the centre regarding an allegation of assault between a detainee, 14, and a youth worker.

"It happened around 8am in the morning," a police spokesperson said. "There are allegations of use of a plastic knife that police are investigating. The youth worker didn't require any medical attention."

The spokesperson said no charges have been laid and police are currently investigating the matter.

Mr Little said PSA has called for therapeutic centres, which offers the kids proper services like counselling and education to help them, and the reintroduction of high-risk offender units, to help minimise the risk of particularly violent detainees. 

"In January, the government issued a number of interim measures but it has never put any more money on the table," he said. 

"We've had nearly three months of 'consultation' on therapeutic and high-risk offender units to separate out the smallish cohort causing a disproportionate danger to staff and other offenders."

Mr Little said rather than properly funding the system the government is creating "a school for crooks".

"Young offenders are exposed to, and radicalised by dangerous criminals," he said.

"PSA members who work in juvenile justice have been incredibly frustrated by the failure to introduce measures and resources that recognise what is required to safely manage high-risk detainees.

"Our members want to help these kids, they want to break the cycle. The last thing they want to see is them going up the road into Long Bay or Cessnock, but to stop that they need preventative measures in place."

A NSW Juvenile Justice Spokesperson said staff safety is a priority and there are many controls in place to support staff to manage the challenging and at times violent behaviour displayed by some young offenders in custody.

"All frontline custodial staff have undergone refreshed protective tactics as well as de-escalation and negotiation training over the last 12 months," they said.

"Juvenile Justice uses a number of tools to manage high risk young people. Detainee Risk Management Programs are individualised risk management plans developed to manage young people who are deemed high-risk.

"These plans can limit their access to programs and place restrictions on who they can associate with. DRMPs are continually reviewed to ensure they provide proper management and oversight of the young person."

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