An out-of-control wildfire burning in Tongariro National Park has spread overnight, now covering an estimated 1000ha.

The large fire in the Central Plateau broke out yesterday, triggering evacuations of trampers and closing a highway last night.

Forty-three hikers and the Mangatepopo Hut warden were airlifted as a precaution with Department of Conservation staff providing welfare at Whakapapa Village.

What caused the fire is unknown.

Fire and Emergency New Zealand said fresh crews of firefighters from Taranaki and Manawatū-Whanganui are being briefed before joining the battle to bring the blaze under control this morning.

Assistant Commander Nick West said the fire grew in size overnight and now covers an estimated 1000ha. It is not under control.

He said six fire trucks and five tankers are on the fireground, supported by six helicopters and two fixed-wing aircraft. A specialist wildfire investigator is also on deck.

West said there are no reports of structures being damaged or destroyed and no residents were evacuated overnight. An aerial reconnaissance this morning will confirm the extent of the fire.

It’s expected to take a full day of operations to bring the fire under control.

West said residents in the area should stay alert to the fire, and keep doors and windows shut to minimise exposure to the smoke.

Anyone who feels unsafe, or is vulnerable to smoke, is being encouraged to self-evacuate and stay with family or friends.

People north of the fire are advised to go towards Tūrangi, and people south to go towards National Park.

State Highway 47, Waimarino to Tongariro, remains closed between the intersections with SH48 and SH46 with no detours available.

The Department of Conservation has closed the Tongariro Crossing and associated areas.

A no-fly zone is in place covering the airspace over the fireground and surrounding area, so that firefighting aircraft are not endangered by other aircraft or drones.