Gassing prison cells is being defended as the least barbaric way to get unruly inmates out of their cell.
RNZ has revealed accounts of two inmates from Auckland Women's Prison who had their cells gassed with pepper spray.
The women said they were also kept in a segregated unit for four months and made to lay on the ground with their nose on the floor by the toilet before they would get fed.
Corrections Association president Alan Whitley said 'cell busting' or bombing is the least harmful method to remove someone from their cells.
It is a special brand of pepper spray, designed for use in small spaces, he said.
The wand goes under the door or through the meal slot where it is charged for two or three seconds at a time.
"The pepper spray goes through the air into the cell, it normally lands on a surface, you try for the back wall of the cell. You don't spray it directly on the prisoner.
"And from there, it fills the cell with atomized pepper spray.
"They start to inhale that they feel the effects of it and you can bring the prisoner out of the cell and fresh air and the effects of that wear off relatively quickly," he said.
The tactic is only employed for prisoners who are endangering themselves, others, or potentially staff.
"It's been used in places where prisoners have been very aggressive, but also harmful to themselves, to bring them out where prisoners are smashing up the cell.
"You want to get them out of the cell before they manage to smash out of the cell and come at you with a weapon."
Whitley does not believe "cell busting" should be stopped and this method is less painful than the alternative.
"The other way that we can a prisoner out of a cell is quite barbaric as well.
"You form up a team outside the cell with four staff members and protective equipment, they have a shield, they open the door, they go and they slam the shield against the prisoner to hold them on the wall while two people grab the prisoner's arms, the shield is moved, and the prisoner's dragged down to the ground."
This method results in more injuries to both staff and prisoners.
The pepper spray is not nice, but you recover from it quite quickly, Whitley said.
These tactics are only used on prisoners who are being non-compliant.
He also disputed the accounts of women inmates being forced to lie face down beside their toilet before they are given food.
"To put a meal into a cell where you've got an aggressive prisoner or a prisoner that is lashing out a staff member, you need to open the meal slot and you need to pass the meal in.
"Quite often while you're doing it, the person will have a crack at the staff member by throwing something out of the slot quite often a body fluid of some sort, or they'll try and grab the staff member's arm causing injury."
Whitley said he had never heard of anyone being made to lay on the ground face down by the toilet, and prisoners are instead asked to kneel at the back of the cell with their hands on the wall.
He said Auckland Women's Prison has had some difficulties in the past, but there was now new management.
Staffing shortages at the prison had also caused tensions because the women were locked in their cells for longer, but that was improving.
He said no one goes to work wanting to use force on a prisoner.
"Staff go to work in all of our prisons in really difficult conditions. They do a fantastic job and they do it day in and day out.
"They go there every day trying to do the best they can with some of the worst people that we've got in New Zealand and I think we need to admire them for that."