Supermarket chain Asda cut its fuel prices to 99.9p per litre today, saying there was "little justification" to charge more than £1 at the pumps.
The price cut was made on petrol and diesel at the company's 176 forecourts.
Commercial director David Miles said: "There is no justification for any major retailer selling fuel above £1 per litre - that is why we are delighted to be able to reduce both petrol and diesel to 99.9p per litre for all our customers in line with falling costs.
"Asda is offering value to all drivers nationwide and we can guarantee all our customers that they'll get a fair price for their fuel no matter what they fill up with at the pump."
The company said that while diesel prices have previously been higher than petrol, current costs mean that this should no longer be the case.
According to website petrolprices.com, yesterday the average charge per litre for unleaded was 103.8p, ranging between 99.9p and 115.9p, while the average for diesel was 105.3p, ranging between 99.9p and 117.0p.
The price of crude oil has been on the rise in recent months, but it is still less than half the 140 dollars a barrel level it reached at its height last year.