Official estimates of how much natural gas is in the country's reserves have been downgraded.
Pohokura is New Zealand’s largest natural gas producer. Photo: Supplied
The Ministry of Business Innovation and Employment estimated the reserves had reduced by five percent.
The figures show there are just under 1985 petajoules of proved plus probable gas reserves in all the known fields in New Zealand.
The chance of any further discovery has been reduced by the government's ban on new offshore oil exploration.
Latest figures show New Zealand's gas supplies will last for another 10.5 years.
The main driver of the decline is a 27.2 percent decrease in gas reserves at the large Pohokura Gas Field, off the northern coast of Taranaki.
The diminished supply of gas is unlikely to affect households, who use just a tiny proportion of the country's gas output. It will likely affect the Methanex New Zealand plant in north Taranaki, which uses 41 percent of all of the country's natural gas output, turning it into methanol.
The company has refused to comment but at the time of the government's moratorium on new exploration, Methanex said it was disappointed at the decision and the lack of consultation with industry.