The department in charge of New Zealand's prisons is scrambling to find out how often specialist riot squads have been deployed to control inmates.

It comes after a Newstalk ZB investigation found Corrections was effectively running blind, despite staff responding to "extremely volatile" events, like riots and brawls.

Acting National Commissioner Leigh Marsh has confirmed there was no central record of when advanced control and restraint (ACR) teams had been sent out.

"Corrections acknowledges that recording deployments was an area that needed further development."

Marsh said work's underway to gather the information.

"A register of ACR deployments has been created; ACR commanders have been asked to recall and record previous activations and deployments over the last 12 months; and in future, centralised records will be kept of ACR deployments."

ACR teams were deployed at Waikeria Prison in the riot of 2020/21. Photo / Brett Phibbs

The major development follows ZB's revelations earlier this year that Corrections didn't keep a close

At the time, Corrections Minister Kelvin Davis said he couldn't "reliably and readily extract" details on how many times the teams have been used since October 2017, and if any requests for support were turned away.

A Corrections spokesperson maintained the department does keep track and, given enough time, would be able to gather the data.

But when ZB asked for the same details under the Official Information Act (OIA), the request was partially refused as it didn't exist.

"The information requested is not held by Corrections and we have no grounds to believe it is held by another agency."

"Requests for the support of the ACR teams are not approved or declined. A request is sent from a prison director or regional commissioner for additional support and the ACR team is deployed."

Instead, Acting National Commissioner Leigh Marsh provided "initial information" about a handful of deployments, including during the Waikeria Prison riot in 2020/21.

"It is important to note that this data is still being validated by Corrections staff. It is not complete but is provided to the best of Corrections' ability at this time," he said.

Corrections also considered charging for another OIA request, in which ZB requested access to internal communications about the teams, before refusing it altogether.

An ACR team is made up of officers who have received additional specialist training, and can be called upon for significant events of prisoner disorder, either at the site they work at, or another site that requires assistance.

Force may only be used lawfully against prisoners when a staff member has reasonable grounds to believe it's necessary, such as for self-defence, to protect another person, or in the case of an escape.