New Zealand's Commerce Commission is investigating rebates and other payments major supermarkets charge to suppliers in an effort to gauge the impact the practice has on competition in the grocery market, the consumer protection agency said Tuesday.

The commission said it discovered more than 50 types of payments charged for shelf restocking and other in-store services, accounting for around NZ$6 billion paid by suppliers to major supermarkets per year.

These payments, identified in a wholesale supply inquiry that launched in September 2024, are made by suppliers to grocery retailers to effectively reduce the final price paid by the retailer. The commission has closed the inquiry, concluding that industry-led changes to wholesale offerings provide a better way to address supply issues than the imposition of more regulation.

"We're not suggesting that the major supermarkets shouldn't be able to negotiate hard for competitive prices," said Grocery Commissioner Pierre van Heerden. "This is about the difference between the prices that large and small retailers have to pay for groceries and the impact of that on competition."

In a statement to MT Newswires, a Woolworths Group (ASX:WOW) New Zealand spokesperson welcomed the commission's inquiry closure report, saying that the company is committed to ongoing dialogue with regulators and suppliers.

FoodStuffs did not immediately respond to a request for comment.