A power outage cutting television and heating for some prisoners sparked a seven-hour protest and resulted in the Otago Corrections Facility being locked-down during Saturday.
The Milburn-based prison was locked down at 10.30am when five prisoners staged a protest after power was cut to their unit, Prison Manager Reti Pierce said.
The five prisoners took part in the "passive protest" in the central yard of their accommodation unit, while other prisoners were securely detained, he said.
The Department of Corrections were tightlipped over the reason for the protest.
However, the Otago Daily Times understands the prisoners were unhappy over having no heating or television to watch - with the Rugby World Cup quarter finals screening that night on free to air television.