Supermarkets advertising "specials" on everyday items need to make sure they're really offering customers a bargain, says Consumer NZ.
Consumer's annual supermarket price survey found half the products tracked over the survey's seven weeks were regularly on promotion.
"We found some products are being discounted so often, shoppers have grounds to question whether the specials are really all that special," Consumer chief executive Sue Chetwin said.
"Price promotions have become the new normal in supermarket aisles. But shoppers face an unenviable task wading through the advertising noise to work out if they are getting a genuine bargain."
Pricing practices have earned both Foodstuffs and Progressive Enterprises a place on the Commerce Commission's roll of the most complained about traders.
Consumer has called for regular price monitoring to ensure consumers aren't being misled about special prices.
"If the savings aren't real, retailers risk breaching the Fair Trading Act," Chetwin said.
The survey has named Pak'n Save as the cheapest store in the six centres where prices were tracked.
Prices were collected for a basket of 30 popular grocery items over a seven-week period at Countdown, New World and Pak'n Save stores.
"Pak'n Save stores came in with the lowest prices, retaining the place the chain has held in nearly every survey over the past 15 years," Chetwin said.
Prices were closer at New World and Countdown. On average, the cost of the groceries at New World was about $3 to $5 higher than Countdown.
The exception was Hamilton, where average prices were level pegging.