The PRA has accused supermarkets of anti-competitive pricing after Morrisons and Asda slashed their fuel prices, with 12ppl off petrol and 8ppl off diesel. Asda said the cuts would mean drivers would pay no more than 102ppl for petrol and no more than 108ppl for diesel, and that it was only passing on reductions.

PRA chairman Brian Madderson said: "There has hardly been any volume this week so dealers could not possibly afford to give away fuel at the prices the supermarkets were charging. Smaller businesses nearer supermarkets are going to feel the pinch."

Even the RAC, which usually urges super-markets to cut fuel prices, only gave a muted welcome to the latest cuts.