The fuel price cuts claimed by supermarkets in mid-March were patchy, and in many cases below the 2ppl headline figure, according to the AA, which said non-supermarket retailers were undercutting superstores in some locations.

In its latest AA Fuel Price Report, it said: "The true meaning of an ’up to 2p’ cut in pump prices is mainly a 1ppl reduction, except for Asda. It also shows that some non-supermarket retailers were still undercutting the superstores despite the price ’skirmish’."

It added: "The Big Four’s generosity has been far from consistent around the country." In February, the AA said that supermarkets had "lost the plot on pump prices". The gap between them and non-supermarket retailers had narrowed to its closest in a year.