Supermarkets are guilty of misleading customers by way of "dodgy discounts" and mis-leading multi-buys", according to consumer watchdog Which?
The company said that many supermarket firms were in need of being more open with consumers, who it said are increasingly worried about the rising cost of food.
Its own research found that rising food prices are one of the top worries among consumers, with 40 per cent claiming that they were likely to cut back on the amount they spend on food over the course of the next few months.
Which? analysed the prices of over 70,000 grocery products, and found "examples of misleading multi-buys that could cost you more and dodgy discounts, where the offer ran for much longer than the item was at the higher price."
One of the deals under scrutiny was the Ocado promotion of a 12 pack of Beck's Bier, which the retailed claimed had been reduced from a price of £12.19 and was now available for £9.
However, the watchdog found that the product had only been made available at the higher price 18 days before the start of the promotion, causing investigators to label the deal as misleading to customers.
The organisation's executive Richard Lloyd led its Make Special Offers Special campaign.
He said: “We’ve found dodgy discounts across the aisles. And with rising food prices hitting shoppers’ budgets hard we think supermarkets are not playing fair.
“The stores have had long enough to sort their act out, so we’re saying enough is enough, it’s time to Make Special Offers Special.”
A spokesman for the British Retail Consortium (BRC), maintained that retailers were commited to giving customers a good deal and that they wanted to offer the keenest promotions and the best value for their customers in what is currently a tough and competitive market.
But he conceded that because of the widespread popularity of supermarket promotions, mistakes were almost inevitable.
He said: “Across the tens of thousands of promotions available every day, regrettably, occasional errors do slip through."