A new report into the Kohuora men's prison in Auckland has found inmates are spending extended periods of time locked in their cells and their rehabilitation needs are not being met.

The Chief Ombudsman, Peter Boshier, today released a report into the treatment and conditions of prisoners at Auckland South Corrections Facility - also known as Kohuora.

Boshier told Larry Williams he's most concerned about the practice of locking prisoners in cells as a way of managing staff shortages and rostering issues.

"What disappoints me is that isn't reaching its full potential. There are a lot of good things going for it, but there is definitely room for improvement.

"Serco has had a bad name in the past, and this prison in South Auckland does have a lot going for it so it wouldn't be fair for me to pile on the blame towards them, but changes do need to happen."

Boshier says staff shortages also negatively impacted on the quality of the case management prisoners experienced

"In the 12 months before the inspection, staff turnover was at 21 per cent. All you can do to manage is lock the prisoners down for long periods, which you aren't allowed to do.

"It leads to a lack of continuity and a positive relationship between the prison guards and prisoners. We miss out on a crucial part of the relationship building."

Serco is taking on 35 of the 36 recommendations made by Peter Boshier in the report.