Unleaded petrol was being sold at an average of £113.01 per litre yesterday, according to the AA – up from 93.98p last year. Industry experts expect it to be £1.50 by September.

And the Prime Minister warned motorists to brace themselves for further crippling forecourt price hikes for at least the next three years.

Gordon Brown blamed conditions in the global oil market, and admitted that Government measures designed to ease the strain on drivers are unlikely to have much impact.

He said yesterday: “The supply of oil that is available over the next few years is less than the demand for oil.

“This year, next year, and the year after – despite the measures we have taken to increase the supply of oil – that demand, particularly from Asia, is exceeding that supply.”

He told executives at internet giant  Google: “Until we have a proper dialogue between consumers and producers that bring supply and demand into a better position, we will continue to have problems.”

His words were met with fury, as the Treasury rakes in more than £100million every month as a result of sky-high diesel and petrol prices.

The Tories savaged Mr Brown and Chancellor Alistair Darling for piling more misery on drivers through punitive rises in Vehicle Excise Duty.

Philip Hammond, the Shadow Chief Secretary to the Treasury, said it “will make life even harder for families already struggling with soaring motoring costs”.

Privately, ministers fear a fresh rash of petrol protests and blockades by hauliers if price rises continue.

Lorry drivers are being hit particularly hard by soaring diesel costs, with some road hauliers forced out of business altogether.

The Road Haulage Association is urging members to demand that the rising costs are met by their customers – which in turn would see further rises for shoppers.

PetrolPrices.com spokeswoman Louise Doherty said worse is yet to come. She said: “Rising petrol prices are forcing drivers to think about getting a diesel car for the fuel efficiency.

“But this will put pressure on the diesel supply and push prices up to the point where diesel is so expensive that even the extra miles per gallon won’t justify the price.”

Diesel models accounted for 45.4 per cent of all new cars sold in the UK last month, said the Society of Motor Manufacturers and Traders.

New diesel models cost on average £1,400 more than petrol ones. The price difference was previously made up after about 45,000 miles – but now the break-even point is pushed back.