Thousands of litres of chemicals have spilled at the Fonterra plant in Edendale in Southland.
Fire crews were called at about 2am to the plant where about 5000 litres of nitric acid and a caustic alkali spilled from storage tanks into a containment area.
Fire Service assistant area commander Dean Chalmers said no-one had been affected by the exposure of the chemcials to the air, and the spill had been contained.
"The bunding that holds the chemicals is holding quite nicely ... and at this point in time the Fire Service is working with Fonterra staff to help make the scene safe and look at the clean-up side of it."
Six fire crews spent the morning at the plant making sure the chemicals did not mix.
Southland's regional council has an investigator at the scene trying to find out what caused the spill and to decide on any further actions.
