The AA has urged the Government to shelve next month's rise in fuel duty after warning that motorists face a new upswing in pump prices.

The motoring organisation said plans to add 1p to petrol and diesel prices from October 1 come at a time when the cost of crude oil and a weaker pound threaten to put additional upward pressure on motoring costs. January's increase in VAT to 20 per cent is set to compound the misery for motorists.

While the AA said average UK pump prices fell for the fourth month in a row during the last month, its latest fuel price report found that drivers were still paying £4.36 a tank more for petrol than a year ago.

AA president Edmund King said the 9p to 10p increase in petrol and diesel prices had landed the Government with a VAT windfall of at least 1p a litre.

"For that reason, the duty hike could be shelved to help economic recovery, ahead of the 2.5% VAT increase next year."

The wholesale cost of petrol has risen by around 2p a litre since mid August and the AA said speculators threaten to increase oil prices to the level that lifted UK petrol prices to May's record high of 121.61p a litre.

Mr King added: "Pump prices remain precarious with the possibility of a new upswing, and it will be bad timing if the 1p-a-litre fuel duty increase in October coincides with another £1 on the cost of a tank of petrol."

Across the UK, London remains the most expensive area for petrol at an average of 116.2p a litre, with Northern Ireland and Wales dearest for diesel at 118.7p. Yorkshire and Humberside is cheapest for both, respectively 114.2p and 117.2p a litre.