A fire has at the former Paper Mill building in Mataura, where toxic aluminium waste is stored, has been put out.
A Fire and Emergency spokesperson said crews had contained the fire inside the building on Kana Street, which was reported about 1.40pm, with more than 30 firefighters in attendance.
The paper mill is where an estimated 8500 tonnes of aluminium waste known as ouvea premix, from the Tiwai Point Smelter, is stored.
A Fire and Emergency spokesperson said the blaze was 30 metres away from the waste and did not pose an immediate threat.
Mataura Southland fire service incident controller Scott Lindsay confirmed to RNZ that sprinklers were set off inside the building, so firefighters used gas suits as a precaution, but the water had not reached the waste product and it had not reacted.
The waste product can react with water to produce toxic gas, and was threatened by flooding in February. Despite warnings and evacuations, the floodwaters did not react with the dross, and residents returned to the town the following day.
Gore District Mayor Tracy Hicks said the Ministry for the Environment recently allayed concerns the waste would react to fire, or that it was anything like what triggered a massive explosion in Beirut this month.
"MFE (The Ministry for the Environment) put out some information then around how stable that particular product is in terms of explosion ... I think the real risk with the ouvea premix is water as opposed to fire."
Firefighters were working to isolate power at the plant this afternoon. They said fire was on a floor beneath the premix, about 30 metres from where it was stored.
The fire covered a 10 square metre area in the hydro generator and was contained within about two hours.
There are other fires burning around the South Island, including a large uncontrolled bushfire at Aoraki/Mount Cook which has been burning for more than a day, and another fire in scrub and pine on the outskirts of Oamaru.
The storage of the waste has been a sore topic for locals, who have been pleading with the government and smelter owner Rio Tinto to have it removed.