Aldi has been crowned the cheapest supermarket for the 13th month in a row, with the average price of a basket of groceries costing £75.25.

The research from Which? found that the discount grocer was £16.55 cheaper than the most expensive supermarket, Waitrose.

While Aldi has retained the title for the past year, the same selection of groceries was £6.65 more expensive in June than in May, at £68.60.

Aldi managing director of buying, Julie Ashfield, said: “We know it’s a difficult time for many and we’re proud to have been consistently named as the UK’s cheapest supermarket.

“In the face of an ongoing cost-of-living crisis, we continue to support our customers when it matters most.”

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The consumer watchdog found Lidl to be the second cheapest at £77.18, while the average basket price at Asda and Tesco was £82.55 and £82.67, respectively.

Although Waitrose was the only retailer to cost above £90, online-only grocer Ocado was just £2.60 cheaper at £89.20.

When considering a larger trolley of 134 items, excluding Aldi and Lidl, Asda was found to cost the least at £333.16, followed by Morrisons at £343.41.

Which? retail editor Ele Clark added: “Millions of people are struggling during the worst cost-of-living crisis in decades, and Which?’s research shows why many shoppers are turning to discounters like Aldi and Lidl.

“Which? believes that supermarkets are currently falling short when it comes to helping shoppers. They have a responsibility to ensure everyone has easy access to basic, affordable food ranges at a store near them, and to provide transparent and comparable pricing so people can easily work out which products offer the best value.”