A fire broke out on a conveyor belt loaded with 27% ammonium nitrate in a fertiliser manufacturing plant. A technician who noticed smoke on the 2nd floor of the dispatch station raised the alarm. The establishment’s internal emergency plan was activated. The dispatch station was shut down (electricity and control air etc. turned off) and the staff were evacuated. The emergency response team brought the fire under control within a few minutes. The internal emergency plan was lifted one and a half hours later. No human or environmental consequences were reported, the conveyor belt involved was melted by the fire and the damage caused could be seen around the area for several metres. The dispatch station had four small intermediate 25 t silos, containing the fertiliser collected by the scrapers from the main storage sheds located a few dozen metres away. The fertiliser was transported to these silos via conveyor belts; it was then weighed and conveyed towards bulk or bag loading stations. The fire broke out on a take-off conveyor belt (located after an intermediate silo containing 12 t of ammonium nitrate) that had been stopped for 15 minutes following the loading of a lorry. The heating of this belt (for undetermined reasons) had caused the fire. No electrical failure or hot work were noted. The decomposition of a few kg of 27% ammonium nitrate on the belt did not seem to be the cause: this type of fertiliser requires a heat source of at least 200°C in order to start decomposing and can only continue if this heat source is maintained. In addition, the shed’s detectors had not reported the presence of NOx, which indicates decomposition. The operator indicated that the conveyor belts in the main fertiliser storage sheds had all been replaced by self-extinguishing belts. The site’s other conveyor belts will also be progressively replaced with self-extinguishing belts according to their age.