Early Christmas cheer for motorists as world oil plunge sees petrol prices slashed to lowest in four years Asda and Tesco knock 2p a litre off petrol and diesel Average petrol price is at lowest since late 2010 Brent crude fell as much as 8% yesterday to below $72 a barrel Oil price now 37% below $115 peak reached in June By Adrian Lowery for Thisismoney.co.uk The falling world oil price has prompted a fresh round of petrol price cuts by the big supermarkets with another 2p shaved off a litre. Falling forecourt prices have been spurred by the recent plunge in the cost of oil. In an early bit of Christmas cheer for UK motorists, Asda said it will knock 2p a litre off its petrol and diesel from tomorrow, and Tesco responded by doing the same from this afternoon. It tanked to its lowest level for more than four years last night after OPEC refused to cut production despite a glut of supply and weak demand. Brent crude fell as much as 8 per cent to below $72 a barrel - a price not seen since August 2010 and 37 per cent below a $115 peak reached in June - as members of the oil cartel stuck to their target of producing 30million barrels a day. Petrol prices hit 131.7p a litre over the summer while the price of diesel was at 136.37p. Average prices have since fallen to 122.62p and 127.13p a litre respectively, the lowest since late 2010. But Asda's latest reduction means drivers will pay no more than 117.7p a litre for petrol at the store and 121.7p for diesel. It is the company's seventh cut in two months and means its petrol has gone down by 9p a litre and its diesel by 8p a litre since the end of September. RAC fuel spokesman Simon Williams said: 'As Opec decided not to cut production yesterday, the Brent crude price dipped to 70.68 dollars a barrel at the end of the day, which is the lowest it's been since June 2010. This means there will be more oil in circulation than there is demand. The result is excellent news for motorists this Christmas, with the cheapest forecourt prices for four years. He went on: 'But if retailers are truly going to reflect the wholesale price savings, today's cuts should be the first of several in the coming weeks. We believe pump prices should fall by well over 4p a litre in the next few weeks, taking the average price of petrol considerably below the 120p a litre mark, which last happened on December 1 2010. OPEC - the Organisation of the Petroleum Exporting Countries - was under pressure from member states including Venezuela to cut production to prop up prices. But, speaking ahead of the cartel's meeting at its headquarters in Vienna, Austria yesterday, the Saudi Arabian oil minister insisted that the market would eventually stabilise itself. Saudi Arabia dominates the 12-member organisation which accounts for a third of global oil output. The Saudis and other wealthy producers are able to cope with lower prices as they battle to maintain market share amid competition from shale oil producers in the United States. But poorer OPEC members such as Venezuela and Nigeria need prices of around $100 a barrel. Venezuelan foreign minister Rafael Ramirez left the meeting visibly angry but Saudi oil minister Ali al-Naimi hailed "a great decision" after what is understood to have been one of the most acrimonious meetings in recent years. Analysts said the price of oil, which has fallen by more than a third in just five months, could fall further as the combination of the US shale boom and weakness in the global economy result in supply outpacing demand. Opec meeting: Oil ministers from the top producer nations' club gathered in picturesque Vienna today