Budget supermarkets Lidl and Aldi have seen the biggest price rises over the past year, according to new research.
Which? found prices were up 23.6% at Lidl and 22.5% at Aldi compared to a year ago.
It compares to 13.2% at Sainsbury’s and 13.6% at Tesco, with Which? having analysed inflation on more than 25,000 food and drink products across eight major retailers amid the cost of living crisis.
However, Which? still found the discount retailers were generally still cheaper than their competitors.
A breakdown of the price rises can be seen in the chart, below.
The research also found shoppers who rely on supermarkets' cheapest ranges are bearing the brunt of grocery inflation, with price rises on value items far outstripping those of branded and premium products.
The price of value range items was up 21.6% in January compared to a year before, well in excess of overall grocery inflation of 15.9%, Which? found.
In comparison, branded goods rose by 13.2% over the year, own-label premium ranges were up 13.4% and standard own-brand items increased by 18.9%.
Its findings suggest those who are likely to already be struggling to feed their families and pay their bills during the cost of living crisis are being hit disproportionately with the sharpest food price increases.
Sue Davies, Which? head of food policy, said: “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.”
However, it comes as consumer confidence has made a surprise rebound from historic lows despite the ongoing cost of living woes, separate figures show.
GfK’s long-running consumer confidence index rose by a significant seven points in February, although the headline score remains at a “severely depressed” negative 38.
Confidence in the general economic situation over the next 12 months is up by 11 points, though it remains at negative 43 and on par with last February.