One crew dealt with the fire to prevent further damage to the vessel, while the others prepared to cool 1,000 tonnes of coal and transport it off site, local media reported.
Fire and Emergency shift manager Daniel Nicholson informed that the coordinating effort was successful as all the relevant authorities were on site.
The heat reportedly caused smouldering of the cargo, which was cooled as it was unloaded.
A spokesman from the operator Swire denied the incident was a fire, noting that the ship was discharging cargo coal at Ports of Auckland when smouldering of the coal occurred, while emergency services were deployed as a precaution, according to stuff.co.
Works in the Port were not disrupted and there was no evacuation. The ship sustained no significant damage.