She toured the Milburn jail yesterday with fellow Labour MP David Clark, who represents the Dunedin North electorate.
Ms Ardern said she was visiting prisons throughout the country to better understand how they operated and to identify systems which worked as well as those which could be improved.
Corrections officer safety was a particular concern, and Labour was determined to reduce the rate of assaults on prison staff, she said.
Ms Ardern supplied the Otago Daily Times with the latest annual data for serious, non-serious and non-injury assaults on staff in New Zealand prisons.
It showed in the 2012-13 financial year there were 11 assaults on staff at the Otago Corrections Facility (OCF), down from 17 assaults in the previous 12-month period.
There were no serious assaults (those warranting hospitalisation for at least 48 hours), but there were five involving injury and another six classed as non-injury assaults.
Nationally, there were at least 348 assaults on prison staff in the 12 months to June 30, of which 13 were serious. Another 105 involved injury.
The highest assault rates were at the Spring Hill Corrections Facility (47), Auckland Prison (45), and Rimutaka Prison (41).
Ms Ardern said the OCF had a vastly different atmosphere to other jails she had visited, and its design was unique, allowing staff more ''time on the floor'' among prisoners.
''I think that makes the prison more manageable day to day and certainly staff are able to do some new and innovative things. The variation between facilities is enormous and the OCF would have to rate pretty highly in terms of the facility.''
As a relatively new prison (2007) it offered a ''really high standard'' of access to rehabilitative programmes and employment training on site, she said. Despite positive elements, the facility continued to have ongoing problems that managers and staff were addressing, Ms Ardern said.
Referrals from Spring Hill had been a ''big change'', and staff were working to alleviate concerns about prisoners' health needs not being met and about inappropriate handling of remand prisoners, she said.
Across the board, Labour was concerned about double-bunking, as it increased the risk of assaults on staff, and Ms Ardern said taking time to properly assess prisoners before placing them in double-bunking arrangements would improve corrections officers' safety.
She was also concerned about whether stab-proof vests were ''as available as they should be'' for staff dealing with maximum security prisoners, and said the problem with some re-integration programmes was there were not enough of them.
Ms Ardern said ultimately it was Labour's goal to reduce the prison muster ''in the first place''.
The figures
Assaults on Otago Corrections Facility staff
2012-13: 11 (5 injury, 6 non-injury)
2011-12: 17 (1 serious, 6 injury, 10 non-injury)
2010-11: 11 (2 serious, 2 injury, 7 non-injury)
