Petrol prices could rise by 8%: Find the cheapest where you live

And the cost of filling up at the pumps could rise by 3% by this August Bank Holiday weekend.

The warning to motorists came from the Retail Motor Industry Independent Petrol Retailers Association (RMI Petrol).

It put the blame for the expected rises on currency movements and world oil price increases.

RMI Petrol, which represents around two-thirds of Britain's 9,000 petrol forecourt sites, said petrol prices could rise as high as 125.9p per litre in the new year, smashing the current record high of 121.61p.

This increase would take into account the rise in VAT and the planned hike in fuel duty.

RMI Petrol chairman Brian Madderson said: "The rebound in crude oil pricing is disappointing but not entirely unexpected. It will further increase pressure on independent retailers who are fighting for survival, especially in rural areas, due to the double hit of falling volumes and tighter margins.

"This crude oil increase will feed through the supply chain and could result in prices going up by as much as 4p a litre in the next three weeks."

He went on: "We also need to remember that the coalition Government did not cancel Labour's Budget commitment to raising fuel duty by 1p a litre from October 1 and a further 0.76p from January 1, with both having VAT added.

"Then we have the coalition's emergency Budget proposal to increase VAT to 20% from January 4, so the outlook remains extremely difficult for motorists and retailers alike. As I forecast earlier this summer, we could be seeing new record pump prices within six months.

"All these trends will add to inflationary pressures in our market and across the economy, threatening higher interest rates in the medium term."

RAC spokesman John Franklin said: "The future looks bleak for motorists, with rising oil prices and further tax hikes.

"The coalition Government have promised to take a look at options to control the price of petrol. However, the planned fuel duty and VAT rise are likely to add a further 5p a litre.

"If the Government really want to help motorists, they should abandon these planned increases."

The AA said average petrol prices had now fallen to 116.6p a litre, with diesel at 119.00p.

AA public affairs head Paul Watters said it was unlikely that there would be a sustained rise in oil prices but that petrol prices were 14p a litre higher than they were this time last year.

He added that drivers in south east England and the Home Counties had suffered an "appalling fuel price lottery this summer", with prices varying by as much as 6p a litre.

Mr Watters said: "Along the holiday routes, we have seen the drivers hitting back. They arrive at an expensive fuel station put in 10-15 of fuel and then drive off to find somewhere cheaper.

"Industry sources tell us that sales are down in some areas and we saw prices fall up to 2p a litre last week in some towns, even with wholesale prices beginning to go up."