Unit pricing shows how much a particular product costs based on weight or volume, which helps shoppers work out the best deals.

However, the Competition and Markets Authority (CMA) has launched a review of grocery unit pricing for both the online and in-store sector to ensure Brits can easily compare like-for-like items to help them get a “fair deal”.

It said “in the context of the rising cost of living, people shopping for food and other essential products need confidence that they have the right information to make great choices”.

The CMA said the review comes amid “recent concerns” and follows on from its investigation of grocery pricing in 2015 off the back of a super-complaint from campaign group Which? to which the CMA was required to respond.

Back then, it concluded that “complexities and inconsistencies with unit pricing may prevent people from spotting which deal gives them best value”.

As such, it is revisiting this earlier work to see if the issues identified in 2015 remain: compliance with the law by retailers, and shopper awareness and use of unit pricing information.

The CMA stressed that this review is at an early stage and it has therefore “not formed a view on these issues”.

‘Supermarket pricing transparency’

George Lusty, senior director for consumer protection at the CMA said: “We know that the increased cost of living has hit the pound in people’s pockets.

“That’s why we’re pressing on with this important grocery unit pricing work to ensure shoppers can more easily compare prices and make choices that are right for them.”

Sue Davies, Which? head of food policy, said: “Grocery prices are a huge concern as households all over the country grapple with the cost-of-living crisis, so it’s timely and important for the CMA to be looking at whether prices are clearly and fairly displayed at the supermarket.

“We know poor, inconsistent and sometimes missing price information is a problem and that’s why Which? is campaigning for pricing transparency from supermarkets, so that shoppers can easily work out which products are the best value.”

Figures from the Office for National Statistics today revealed one in five people are cutting portion sizes while an equal number are eating food which is past its sell by date as they struggle through the cost-of-living crisis.

Separate data from consumer research company Kantar also revealed grocery price inflation hit a record high of 16.7%, as shoppers were warned annual grocery bills would be £788 higher if they didn’t change their behaviour or cut costs.