Two helicopters and three crews are battling a scrub fire near Kingston on the border of Otago and Southland.

Two helicopters have been fighting the fire since first light.

Fire and Emergency were alerted to the fire at 2.30am, but crews were unable to access it due to the terrain.

Firefighters from Kingston, Garston and Athol returned at first light with two helicopters.

A Fire and Emergency spokesperson said there are no reports of any structures being threatened, but the fire has burnt through about seven hectares of scrub.