Hundreds of corrections staff are assaulted by prisoners each year, with new statistics for the period between January and August last year showing a total of 295 incidents.

Statistics released to the Herald under the Official Information Act detail the number of assaults on staff in New Zealand prisons over the past six years.

Figures show the highest number of assaults over the past four years took place at Mount Eden Corrections Facility in central Auckland, with the total number of assaults for the January-August 2017 period equalling 48.

Also accumulating high staff assault numbers this year were Hawkes Bay Regional Prison, with 36 assaults, and Manawatu Prison with 29 assaults.

The Manawatu Prison assault numbers are comparatively high when taking into account the number of assaults to the prison's inmate capacity. The prison has a maximum capacity of 290, compared to Mt Eden which holds 1046 and Hawke's Bay with 722.

Despite having one of the highest number of assaults in 2017, the Palmerston North facility remained in the lower percentage for assaults the previous five years.

Department of Corrections acting deputy chief executive of corporate services Richard Waggott said the department currently employs over 9000 staff members, and manages approximately 10,400 prisoners in 18 facilities nationwide - as well as 30,000 community based offenders.

He said of the 18 facilities, Mt Eden presents a unique challenge due to it primarily being a remand facility with a turnover of prisoners significantly higher than that of other prisons.

Figures show the highest number of assaults over the past four years took place at Mount Eden Corrections Facility in central Auckland.

The highest record of assaults in the past six years was at Mt Eden in 2015, with a total of 88 assaults; broken down by 48 assaults with no injury, 39 assaults, and 1 serious assault.

Additionally, Auckland Prison has featured in the top three highest number of assaults for the past five years, followed by Hawkes Bay Regional Prison which has featured the past four years.

Auckland Prison also had the highest number of serious assaults out of all prisons in the past six years, with eight serious assaults taking place in 2016.

While Auckland Prison's status as NZ's only maximum security prison could account for its high figures, no correlation could be made for Hawke's Bay Regional Prison.

Waggott said understanding and managing the risk of violence is a challenge common to all correctional jurisdictions.

"As you will appreciate, we manage some of NZ's most dangerous people in an environment that can be complex and challenging," he said.

"While Corrections considers no assault to be acceptable, we acknowledge the reality that these incidents do occur. Despite our best efforts to ensure risks are mitigated, we cannot prevent all assaults."

In 1998/99 there were 97 serious assaults on staff. By 2014/15 this had fallen to nine serious assaults.

Waggott said despite a 23.52 per cent increase in the prison population since 2012, the rate of assaults on staff had only increased by 0.4 per cent.

"Since the late 1990s, the rate of staff assaults in prisons has fallen dramatically and remains low," he said.

"For example, in 1998/99 there were 97 serious assaults on staff. By 2014/15 this had fallen to nine serious assaults."

He said staff safety is of paramount importance to the department, with many new initiatives working towards reducing the risk of assault.

In 2016 the department launched its new health and safety strategy 2016-2020 Everyone Safe Every Day. Some of the achievements in this area included introducing body cameras and stab-resistant armour and deploying smart phones with safety applications for community-based staff.

More recently, the Corrections Amendment Regulations came into effect, allowing prison directors to issue individual pepper spray canisters to custodial staff members.

Waggott said strong action is also taken to ensure that prisoners are held to account for their behaviour whenever they use violence.

"We support staff and prisoners who have been the victim of assault and provide assistance in reporting the incident to the NZ Police.

"The police determine whether or not criminal charges will be laid in relation to an assault. Prisoners who use violence can also be charged through the internal misconduct system."