A union says an attack on a prison guard at a Northland prison facility which left them with significant facial injuries is not an isolated incident.
The Corrections Association of NZ understands guards at the Kahu Unit at Ngawha Prison were unlocking prisoners from cells when the "unprovoked attack" occurred.
Association vice president Paul Dennehy said the guard suffered "significant facial injuries", which he believes includes a broken nose and jaw.
He said this was not an isolated incident, with figures released under the Official Information Act obtained by the union showing violent attacks are on the up.
"Assaults on staff across the whole country have been on the rise for several years," he said.
He was not sure of staffing levels at the prison when the incident took place, but he said understaffing is an issue at prisons around the country.
Paul Dennehy said many attacks on staff are unprovoked.
"We don't know it's going to happen. We could be talking with a prisoner, the next thing that prisoner or another prisoner blindsides us and attacks, we've got no way of mitigating or defending ourselves immediately."
The association has pushed for prisoners to be held accountable for their actions that go against the rules
"They should be held accountable. But increasingly, we're finding that's not the case. They can be non-compliant, they can be assaultive, they can be verbally threatening, they can be physically attacking us. There are very few legal consequence, within the prison or with police charging them," Dennehy said.
"We work very hard to help rehabilitate prisoners, because one day they are going to be our neighbours."
The Department of Corrections has been contacted for comment.