Shortages of items such as bread and dairy products are foreseen at supermarkets, due to the closure of the Maui gas pipeline.
Some Countdown and Woolworths supermarkets were limiting the number of loaves of bread that customers could buy on Thursday.
Progressive Enterprises says instore bakeries are still operating at Countdown.
Spokesperson Luke Schepen told Morning Report that many stores have shortages of some brands of bread already.
The Food & Grocery Council says even its largest members who diligently plan for the unexpected were taken by surprise, and few companies were aware of the vulnerable state of the gas supply.
The closure of the pipeline has left many commercial customers with no gas and no backup option.
The LPG Association says installers are busy this week as many small businesses turn to bottled LPG.
Meanwhile, the Petroleum Exploration & Production Association says gas reserves in Taranaki may not be larger enough to justify building another pipeline in the upper North Island.