Prisoners were evacuated to the yard at Spring Hill Corrections Facility in Waikato Tuesday evening after a fellow inmate lit a fire in their cell.
A Corrections spokesperson told 1News the fire was quickly extinguished.
"However Fire and Emergency New Zealand were called as a precaution.
"There was no threat to the wider security of the prison but due to a large amount of smoke, other prisoners in the unit were evacuated to a recreation yard. Once the smoke has cleared, the prisoners will be returned to their cells.
"Two staff members were taken off site to have a medical check, and health services at the prison will check on the other prisoners’ wellbeing this evening," the spokesperson says.