Motorists are to see a further fall in the cost of filling up after three of the UK's major supermarkets stepped up their forecourt price war.

Sainsbury's and rival Asda will cut the price of diesel by up to 2p a litre and unleaded petrol by a penny from tomorrow.

Tesco, which is Britain's biggest petrol retailer, will cut unleaded petrol by 1p per litre, with diesel reducing by at least 1p a litre, although some sites will get a 2p a litre price cut.

The moves follow a decline in the price of Brent crude oil, which is now below 90 US dollars a barrel due to weaker global demand.

This means motorists are benefiting from some of the cheapest prices for over three years.

Supermarkets have been slashing forecourt prices as part of their wider effort to win back grocery customers from discount rivals Aldi and Lidl.

The AA said a typical 50 litre tank of unleaded petrol now costs around £2.50 less than it did a year ago and a 55 litre tank of diesel is around £4 cheaper.