Amendments to the Crimes (Administration of Sentences) Act 1999 now means inmates who misbehave or assault staff will have prison privileges withdrawn without it affecting other charges.

The Audit Office found violence in prisons has surged to 25 assaults per 100 inmates, from 15 per 100 in 2012, while the population has grown 40 per cent.

Similarly, the Department of Justice data shows that the rate of inmate on staff assaults has increased, nearly tripling between 2012 and 2018 from 0.58 to 1.53 per 100 inmates.

Stewart Little, general secretary of the Public Service Association, said this is a significant win for prison officers, including those who work at the Junee Correctional Facility.

"We need to be very clear: if you assault a prison officer who's in the course of their duties, then you get extra jail time," he said.

"These laws were introduced for good reason, to keep people, who already have a highly dangerous job, safe.

"The PSA took this fight to the government and is pleased to see they've acquiesced to improve the safety of our jails."

Mr Little said the recent Audit Office report is a clear signal to the government that urgent reform is needed in the system.

The move follows a District Court decision in February, which overturned an inmate's 20-month prison sentence for assaulting an officer at Goulburn's High Risk Management Correctional Centre.

The Director of Public Prosecutions is seeking a judicial review into the decision.

Minister for Counter Terrorism and Corrections Anthony Roberts said these changes will ensure officers are able to do their job safely, efficiently and with authority.

"It also sends a clear message to all inmates who choose to assault our staff that they will face the full force of the law and they will be punished," he said.

Corrective Services NSW Commissioner Peter Severin said the legislative changes were part of our ongoing commitment to enhancing officer safety and their ability to manage difficult inmates appropriately.

"These amendments will ensure that staff within the HRMCC and elsewhere, are protected," he said.

"Our officers can now be confident that the behaviour management program framework, which helps to maintain safety and security in the centre, does not undermine criminal or offence-in-custody proceedings."

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