Mr Langley said Corrections managed some of New Zealand's most difficult and challenging citizens.
"Violence is always a risk as many offenders resort to violent behaviour as a means of resolving issues and of expressing themselves. Prisoners can be volatile and unpredictable and many have long histories of antisocial behaviour."
The department had a zero tolerance policy toward prisoner assaults on staff and other prisoners. No assault was acceptable. However, from time to time prison attacks did occur.
Mr Langley said staff safety was the department's priority.
Corrections would not tolerate prisoners using violence against staff or other prisoners, and when this did occur those involved would be held to account.
"Custodial staff received specialist training in tactical communications, de-escalation techniques and negotiation to de-escalate volatile incidents and manage non compliant prisoners. This training provides staff with the skills to remove themselves from dangerous situations where a control and restraint team is not an immediate option or cannot respond in time."
In addition, personal protective equipment was available, including slash-proof gloves for searching. All sites had access to pepper spray and stab resistant body armour which was used, when approved, in planned events.
And Corrections had recently completed a concept trial of on-body cameras and was now testing a small number of cameras to ascertain if they enhanced the safety of Corrections officers.
"Feedback from staff and prisoners suggests wearing on-body cameras has had positive effects on prisoner behaviour and has assisted in de-escalating potentially violent situations."
Mr Langley said the department was in the second year of the Staff Safety Plan which aimed to reduce the number of serious assaults and violence in prisons and the community.