The prices of supermarket value items are increasing at a level that is exceeding grocery inflation, meaning shoppers relying on the cheapest product ranges are feeling the pinch the most.

Value items rose 21.6% in January compared to last year, well above the rate of grocery inflation of 15.9%, according to research by Which?

Branded items increased 13.2% in January while own-label premium products were up 13.4%. Standard own-brand items increased 18.9%.

The research analysed inflation on more than 25,000 products at Aldi, Asda, Lidl, Morrisons, Ocado, Sainsbury’s, Tesco and Waitrose.

Value items surged in price including Sainsbury’s muesli, rising by 87.5% from £1.20 to £2.25, while Tesco’s tins of sliced carrots increased by 63% from 20p to 33p. Asda’s pork sausages were up 58.2% from 80p to £1.27.

Which? head of food policy Sue Davies said: “It’s clear that food costs have soared in recent months but our inflation tracker shows how households relying on supermarket value ranges are being hit the hardest.

“Supermarkets need to act and Which? is calling for them to ensure everyone has easy access to basic, affordable food ranges at a store near them, particularly in areas where people are most in need.

“Supermarkets must also do more to ensure transparent pricing enables people to easily work out which products offer the best value and target their promotions to support people who are really struggling.”