Petrol prices have fallen for the first time since the 1p fuel duty reduction in late March, the AA said today.

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 yesterday, 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.

"It's nice to know that prices can go down as well as up," said RAC motoring strategist Adrian Tink.

"Like the recent fuel duty cut, the fear is it will only be a short-term relief. With continued volatility in the oil market, our hopes would seem to lie with there being a price war between the supermarkets as we saw towards the end of 2008."