A major fire which has swept through the Awarua wetlands near Invercargill is expected to be brought under control by the end of Tuesday.
The fire began about 6pm on Monday and has burned through more than 450 hectares of conservation land, with warm north-westerly winds fanning the flames.
The blaze was too big to extinguish overnight. Crews were back on the job at first light on Tuesday with three helicopters in the air.
Southern Rural Fire Authority spokesperson Sally Chesterfield says the winds are not as strong as Monday and crews feel they are getting the fire under control.
No homes are threatened and police are investigating what started the blaze.
Ms Chesterfield says the Awarua wetlands are a globally recognised sanctuary.