The Department of Corrections has hit back against criticism from the Chief Ombudsman following inspections last year of Christchurch Men's and Whanganui Prisons.
Peter Boshier described the prisons as 'undignified and barren', and the progress made by Corrections since his last visit as "glacial".
"The apparent inertia that seems to afflict Corrections in implementing change adds to my frustration at the glacial pace of progress in improving conditions and treatment for prisoners and undermines public confidence in the department," Boshier said.
In his inspection of Christchurch Men's Prison last year, the Chief Ombudsman found that of the 54 recommendations made in 2017, 27 had not been achieved and 12 only partially achieved.
Boshier remained concerned about the prevalence of the use of force in the prison's Intensive Supervision Unit.
National commissioner Rachel Leota said a growing number of prisoners with gang affiliations, as well as more people coming in with a history of extensive methamphetamine use had created challenging conditions for prison staff.
"Prisons are reflective of what occurs in our communities and in recent years the environment in which Corrections operates has changed significantly.
"Whilst the prison population has reduced significantly since 2018, there is a growing number of people in prison with a history of extensive methamphetamine [use] which is associated with a significant and lasting impact on mental and emotional function."
"The number of prisoners affiliated with a gang has increased by almost 120 percent with resulting increases in instances of violence and aggression, and our efforts to sustainably resettle people into the community have become more challenging due to demand for accommodation."
She said the department welcomed the inspections but the nature of the reports did not reflect the "hugely challenging" work Corrections' staff did and the progress that had been made.
This included the reduction of the prison population by 22 percent and the use of double bunking by almost 40 percent since March 2018 and the launch of the new strategy Hōkai Rangi.
Leota agreed vulnerable prisoners should not be kept in dry cells - rooms without a toilet or sink - however in the case of Whanganui Prison, when the Intervention and Support Unit was full there was not a better option.
"The alternative would mean moving the person to another prison which could significantly impact support they may be receiving from their friends and family, destabilise them further and exacerbate their mental distress."