Firefighters have contained a blaze at the Ballance fertiliser works at Kapuni in south Taranaki.
The fire started around 9.30am and was located on the roof in one of buildings of the plant, a fire service spokeswoman said.
The fire was under control by midday and the operation was winding down.
The factory, 85km south of New Plymouth, is the country's only ammonia-urea manufacturing plant.
The plant was evacuated and no injuries were reported.
