Tesco and Morrisons have followed after Asda cut 2ppl off the price of diesel, bringing its national price cap down to 97.7ppl while unleaded remains at 99.7ppl.

Andy Peake, Asda’s senior petrol director, said: “We’re delighted to be the first retailer to take diesel to its lowest price level in over six years. This latest announcement shows that we’re committed to being the driving force behind lowering fuel prices across the UK regardless of where you live.”

RAC fuel spokesman Simon Williams said: “We would have liked to have seen a cut sooner, and one that goes further, to more closely reflect the price retailers have been buying diesel for, but this is nevertheless good news for motorists. Diesel has been sold on the wholesale market for less than unleaded petrol since early last month, yet drivers have had to wait more than six weeks for this to be only partially reflected at the pumps.

“The wholesale falls are driven by a world currently awash with oil, which dropped to just $26 a barrel this week, a 75% decline from its $115 high 18 months ago. This turned up the heat up on the supermarkets and big fuel retailers to cut the price of diesel.

“Data from RAC Fuel Watch suggests however that the pressure on prices remains, and we believe there is further scope for between 1ppl and 2ppl to come off the price of a litre of diesel within the next fortnight. There remains a 5ppl gap between the wholesale prices of both fuels.

“Nonetheless, we expect this latest price cut to be the trigger for the UK seeing the average price of diesel being sold on forecourts falling below the £1 mark – something that hasn’t happened since the end of March 2009.”