Firefighters are battling a blaze near Waiouru, the second in two days sparked by military training.
The fire began during a live firing exercise conducted by the Singaporean Armed Forces on the Waiouru training ground in the central North Island.
A Defence Force spokesman said five civilian helicopters and one Air Force helicopter were fighting the blaze, which was contained in a five-hectare gully of dense vegetation in the Three Kings area.
"There is no risk of the fire breaching the training area boundary," the spokesman said.
He said the total area burnt was about 350 hectares and no one was injured.
The fire comes a day after a substantial fire on an army rifle range in West Melton, about 20km west of Christchurch, which broke out shortly after a live firing exercise that included throwing hand grenades.
Sixty firefighters and 40 police staff, along with six helicopters and 18 ground-based appliances, were needed to fight the fire.
Nearby buildings and houses were evacuated, but no damage was reported.
Burnham Camp commander Major Bill Blair said a court of inquiry would investigate what happened before the fire broke out and would "almost certainly" look at whether changes need to be made to guidelines around holding live firing exercises on hot, dry days.
A nearby resident, Jerry Larason, said the exercises were bound to cause trouble.
"You don't need to be a rocket scientist to know that if you throw a grenade around on a tinder-dry field you're going to have problems," he told 3 News.