The country's biggest liquor retailers have agreed to allow government officials access to their sales and price data as part of an investigation into minimum pricing for alcohol.
The Ministry of Justice is looking at whether such a regime would result in young drinkers and heavy drinkers consuming less alcohol.
Officials have met supermarket operators Foodstuffs and Progressive and liquor retailers Super Liquor, Liquor King and Liquorland.
The companies don't want to reveal how much they pay suppliers for alcohol but have agreed in principle to allow access to their retail sales and price data.
Documents released under the Official Information Act show the ministry has had legal advice that it cannot make the information public because of commercial sensitivity.
The ministry is due to finish its investigation by the end of August.