Some chains also cut prices last week

Asda was first to announce a cut of 1p a litre from Saturday morning, a move swiftly followed by Tesco and Safeway.

Sainsbury's said it would match reductions on a local basis.

The cuts comes just a week after many supermarkets and the major petrol companies reduced their prices by between 1p and 2p a litre.

The latest fall in prices was welcomed by motoring organisations as a step in the right direction.

Richard Freeman, of the AA, said: "There was lot of concern that the price of petrol would increase in the run up to conflict in the Gulf so the fact it is falling is very positive.

"It is also typical of the supermarkets to be leading the way in the UK.

"Since they entered the petrol market in the mid 80s they have consistently been the cheapest."

Crude price

The end of the Iraq war has been cited as one of the reasons for the cut in forecourt prices in Britain.

The average price of crude oil has fallen from around 30 dollars a barrel earlier this year to about 24 dollars a barrel on Friday.

An Asda spokesman said: "We wanted to pass on the continuing fall in the price of crude to our customers as soon as possible."

A Safeway spokeswoman added: "The cut reflects the lower costs that we are receiving from the petrol companies."

Two of the major petrol giants, Esso and BP, said they would continue to monitor prices locally and lower them where necessary.