More than 1800 emails have been sent to the Government's dedicated "Price Watch" inbox since it was launched on Monday amid accusations of price-gouging during the country's Covid-19 lockdown.
Many of the emails related to food staples, such as vegetables, flour, bread and meat, a Ministry of Business, Innovation and Employment spokeswoman said today.
"Given the volumes, individual responses would be untimely but MBIE is working hard to contact firms and understand the reasons for price increases," the spokeswoman said.
"We are working closely with supermarkets, and growers, to understand the reasons for the price increases. We understand that there are many valid reasons for various price increases."
Some price increases would have occurred regardless of Covid-19, while others can be explained by fewer discounted lines, the spokeswoman said.
Other products and services which had featured frequently in the emails were cigarettes from non-supermarket sources, hand sanitiser, face masks, rental vehicles and other travel-related purchases, whiteware and electronic goods, she said.
"We do not wish to burden firms at this time as they are busy providing essential goods and services to the nation. At the same time we want consumers to be confident that prices are fair and equitable."
Earlier this week, Prime Minister Jacinda Ardern told Kiwis to report unfair high prices they encountered.
Shoppers are limited as to where they can buy groceries during the month-long lockdown, with only supermarkets and some dairies open. Other shops, such as fruit and vegetable stores and butchers, must stay closed.
However, shoppers quickly began complaining of price-gouging after the lockdown began on March 26.
They also complained supermarkets had dropped specials.
Countdown said on Monday it was bringing back special deals for customers.
The company said customers would "start to see specials return in stores nationwide over the course of this week and next as supplies rebuild and the country starts to settle into a calmer shopping pattern".
"We are feeding more people than we ever have in our history. We made the decision not to go ahead with planned promotions last week because we simply didn't have the stock in store for our customers'', Countdown managing director Natalie Davis said.
Rival Foodstuffs, which operates Pak'nSave, New World and Four Square, had also needed to catch up on stock issues after increased demand before the lockdown.
Specials had not disappeared and supermarkets were not price gouging, North Island chief executive Chris Quin told Mike Hosking on Newstalk ZB this week.
Commerce Minister Kris Faafoi had been quick to contact supermarket bosses over the price-gouging accusations, Ardern said.
Last week, Faafoi directed the Commerce Commission to "show some flexibility" on competition laws to recognise the national emergency. However, price gouging or hoarding won't be tolerated, he said.
Ardern said at one of her daily press conferences this week the most common complaint to the Price Watch inbox had been about cauliflower prices - up to $13 each - but hand sanitiser, bread, meat, face masks and garlic also featured.
A business legally had to have a good reason to increase prices and the complaints would be taken seriously, she said.
"The process for dealing with complaints is being worked through... and we will involve traders so they have a chance to respond."