The UK's cheapest supermarkets in March have been named, and budget favourites Aldi and Lidl have taken top spots.
Aldi topped the list with a basket of 41 items costing £72.54, just 25p less that its close competitor and the second place supermarket, Lidl.
Meanwhile a basket with the same items would cost £20 more - £92.55 - at the most expensive supermarket, which was found to be Waitrose.
As well as basket shops, larger trolley shops were compared to see which supermarket offered the best rates. This comparison of 137 items – the original 41 as well as another 96 - included branded products such as Andrex toilet paper and Cathedral City cheese.
Aldi and Lidl aren't ranked among trolley shops as they don't have as many large supermarkets with branded products.
As a result, Asda was found to be the cheapest for the larger collection of items, costing £343.91, followed by Sainsbury’s, costing £9.25 more. Waitrose was found to be £41.83 more expensive than Asda.
Which?, who carries out this research, said the findings demonstrated that shoppers can make considerable savings on their groceries depending on where they buy their food. However, it said many of the major supermarkets had not done enough to support their customers during the cost of living crisis.
The watchdog said retailers should be helping customers by making sure affordable basic ranges were available in all branches including smaller convenience stores.
Which? Retail editor Ele Clark said: "We know people are suffering through the worst cost-of-living crisis in decades and the price of food and drink has skyrocketed no matter where you shop.
"However, our monthly supermarket analysis shows you could save £20 on a basket of everyday groceries at the cheapest supermarket compared to the priciest one.
"Supermarkets aren’t currently doing enough to help customers.
"Which? believes the big retailers have a responsibility to ensure everyone has easy access to basic, affordable food ranges at a store near them, and to provide transparent pricing so people can easily work out which products offer the best value."
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