The Ministry of Justice says it has "almost completed" a review of court custodial cells throughout New Zealand, saying all but nine courthouses have been reviewed.

There are 367 custodial cells across 57 courts. The ministry says police bring about 50,000 people into the cells for court appearances each year. Corrections and other agencies also bring many people through custodial cells every year, some on multiple occasions.

The Independent Police Conduct Authority released a report on 17 March 2016 into the death of Dwayne Walters in a cell in the Papakura courthouse on 4 May 2015.

The report says the condition of the custodial cells was a contributing factor in Mr Walters' death.

Deputy Secretary District Courts and Special Jurisdictions Karl Cummins says the ministry was saddened by Mr Walters' death.

"We acknowledge that the condition of the cell was a contributing factor in Mr Walters' tragic death. We want to publicly express our condolences to Mr Walters' family," he says.

Mr Cummins says there were different standards when most courthouses were built and as part of the review court custodial cells have been assessed for a number of criteria, including risks to detainees, either from self-harm or assault, and to Police and Corrections staff from assaults.

"Despite the damage the custodial cells often suffer as a risk of vandalism, most were generally well maintained," he says.

"However, we also found some matters that need to be addressed in some custodial cells, including ligature points and the need for surveillance so Police officers can keep a better eye on detainees."