Supermarkets are duping customers into paying more for groceries which are supposed to be on special offer, a new campaign suggests.
Consumer group Which? said research shows that supermarkets have been selling products in offers that do not give shoppers a real deal.
Which? analysed more than 70,000 grocery prices and found examples of misleading multibuys which end up costing consumers more and dodgy discounts where the offer ran for much longer than the item was at the higher price.
For instance, it found a Sainsbury's special offer for Carex Aloe Vera & Eucalyptus Moisturising Antibacterial Handwash, where the item was priced at £1.80 for seven days, then was on offer at "was £1.80, now 90p" for 84 days.
Ocado sold a 12-pack of Beck's beer as "was £12.19, now £9" for almost a month but had only sold the item at the higher price for three days.
Asda increased the regular price of Muller Light Greek Style Yoghurt from £1.50 to £2.18 before it went on a "two for £4" offer, costing shoppers £1 more. It also increased the price of Uncle Ben's Express Basmati Rice from £1 to £1.58 before offering for "two for £3" and then returning the rice to £1 when the offer ended.
Which? executive director Richard Lloyd said the findings come at a bad time for consumers.
Four in 10 consumers are likely to cut back spending on food in the next few months, while eight in 10 are looking out for deals in supermarkets to save them money, 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," Mr Lloyd said.
"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."