Large quantities of ammonium nitrate are being stored on a rural Waikato property very close to a major gas-pipeline, Fire and Emergency (FENZ) says.
When ammonium nitrate is heated to 230 degrees Celsius, such as being involved in a fire, it can become unstable and explode.
In 2020, over 200 people were killed when the chemical exploded in Beirut.
While the likelihood of the chemical exploding was low, characteristics of the site potentially increase the risk, FENZ said.
If an explosion ruptured the underground pipeline it would significantly increase the scale of an emergency.
District manager Daryl Trim said FENZ took the safety and welfare of its people and the community very seriously.
''In March this year we asked the company to consider finding a safer long-term storage site for this material.''
Under the Health and Safety at Work (Hazardous Substances) Regulations 2017, FENZ has a role to review emergency response plans for sites storing hazardous substances.
''We've also reviewed the company's emergency plan and made recommendations for it to be changed.''
It was developing a tactical plan for any emergency on the site, Trim said.
''This includes situational awareness of the site and surroundings, planning for a specific Fire and Emergency response and measures to protect our people and nearby communities, including how we would evacuate people.''
The presence of fire, heat or organic material like hay near ammonium nitrate could trigger or accelerate a fire.
WorkSafe said the business storing the chemical was issued a Location Compliance Certificate for the storage of ammonium nitrate in March, 2023.
It said the storage met the requirements of the Health and Safety at Work (Hazardous Substances) Regulations 2017.
Location Compliance certificates were issued by a competent person who was independent of WorkSafe.
Emergency management requirements were covered under the Location Compliance certificate.
WorkSafe said it did not know the amount being stored, but the site was certified to store up to 349 tonnes.