The consumer champion’s food and drink inflation tracker analysed prices on more than 25,000 food and drink products at Aldi, Asda, Lidl, Morrisons, Ocado, Sainsbury’s, Tesco and Waitrose.

The analysis covered the average price of the products in the three months to the end of February 2023 compared to the same period last year.

Biggest price rises

The items where the average price has risen the most were Asda’s Free From Special Flakes (300g) and Waitrose’s Essential Italian Mozzarella Strength 1 (drained 150g) – which went from 62p to £1.43 (129%) and 80p to £1.77 (121%) respectively.

Morrison’s Free From Corn Flakes (300g) also rose significantly from 60p to £1.29 (115%).

Sainsbury’s Hubbard’s Foodstore Water (2L), Tesco Creamfields French Brie (200g) and Lidl’s Chene D’argent Camembert (250g) have also more than doubled in price over the past year – going from 17p to 35p (106%), 82p to £1.65 (103%) and 99p to £2 (102%) respectively.

Which? found a range of everyday items and own-brand products in each supermarket’s list of groceries with the highest inflation – including milk, meat and fruit.

Researchers found that budget (22.9%) and own-brand (19.7%) items were subject to higher rates of inflation than premium (13.8%) and branded counterparts (13.3%).

When Which? looked at inflation by supermarket it found that while the discounters remain generally cheaper than bigger rivals, it seems they have less room for flexibility when it comes to passing costs on to customers.

The tracker shows prices were up 24.4% at Lidl, compared to 22.7% at Aldi, 17% at Asda, 16.7% at Morrisons, 14.2% at Waitrose, 14.1% at Sainsbury’s, 14% at Tesco and 10.3% at Ocado.

Sue Davies, Which? head of food policy, said: “Worryingly our tracker shows that some everyday essentials have more than doubled in price over the last year – with cheaper own-brand items particularly hard hit.

“Supermarkets need to step up and ensure everyone has easy access to basic, affordable food ranges at a store near them, particularly in areas where people are most in need.

“Retailers must also provide transparent pricing so people can easily work out which products offer the best value.”

What do the supermarkets say?

In response, Lidl claimed that Which?’s findings were “incorrect” and said the tracker included data for products that Lidl doesn’t even sell. Aldi declined to comment.

An Asda spokesperson said: “We’re working hard to keep prices in check for customers despite global inflationary pressures and we remain the lowest-priced major supermarket.”

A Morrisons spokesperson said: “This is an unprecedented period of inflation and we are working hard to keep prices down and competitive for our customers while maintaining high standards and availability in all our stores.”