Petrol prices have fallen for the first time since the 1p Budget-announced fuel duty reduction in late March, the AA has said.
The average price of petrol has gone down 0.22p a litre, while diesel has decreased by 0.53p a litre.
The AA said the cuts announced by supermarkets on Monday had contributed to the fall.
As of Tuesday, the average cost of a litre of petrol was 137.21p, with diesel at 142.51p.
Average prices on May 10 2010 were 121.60p a litre for petrol and 123.05p for diesel.