PETROL prices have reached an all-time high as the rising cost of oil brings more misery for motorists at the forecourt.

The average cost of a litre of unleaded fuel hit 137.44p yesterday, exceeding the previous record of 137.43p set last May.

Fuel experts at the AA say it will soon cost more than £100 to fill up the tank of an average family car, and have called on the Treasury to scrap fuel duty hikes planned for the summer.

The gloomy news for car and van owners comes as a new survey shows motorists in the UK are becoming increasingly angry at the Government's failure to keep costs down.

The high cost of petrol has been caused by ongoing tensions in the Middle East and over Iran's nuclear programme.

The price of Brent crude oil hit a 43-month high on Thursday, peaking at $128.40 a barrel in New York. British motorists are also being affected by the weakness of the pound on the international money markets – oil and petrol is bought and sold in dollars.

AA President Edmund King said: "This new record for petrol and diesel just confirms what every family and business knows: fuel prices are hurting them badly and there seems no stopping them.

"Britain cannot get back on its feet if fuel prices hold drivers and business to ransom every time market sentiment takes hold."

According to the price comparison website petrolprices.com, the average cost of a litre of unleaded petrol in Glasgow yesterday was £1.36, while the cheapest, at £1.31, could be found at Morrisons supermarkets.

In Edinburgh, prices varied between £1.34 and £1.39 a litre, while in Aberdeen, Scotland's oil capital, fuel costs ranged between £1.31 and £1.41 a litre.

Supermarkets are currently engaged in a price war, with several offering discounts on petrol to motorists who shop in their stores.

Morrisons is offering 15p off every litre of fuel to shoppers who spend £60 or more in store, while Tesco has just ended a similar scheme that gave drivers a 10p discount in its garages.

The news of spiralling prices comes as a 5p discount in petrol comes into force on Orkney, Shetland, the Hebrides, the Firth of Clyde islands and the Isles of Scilly, where fuel is traditionally more expensive.

However, some MPs have accused petrol companies of profiteering by raising prices in line with the discount, leaving drivers no better off.

The high cost of filling a tank has sparked anger among many motorists, who are also having their household finances squeezed by the rising cost of utilities and groceries, and increases in VAT – all while wages are stagnating.

A YouGov poll for the car website Motors.co.uk found that 80% of motorists think the Westminster Government isn't on their side, while more than a quarter are cutting back on their car use. An overwhelming majority also said that fuel prices are their biggest concern.

Phill Jones, the site's commercial director, said: "It appears recent efforts by the Government to improve its poor reputation with motorists have failed, as an unacceptable level of drivers are being forced to make sacrifices in their life to simply afford to run their cars."

A Treasury spokesman said: "At the Autumn Statement, the Government took more action to help households with motoring costs by freezing fuel duty until August and scrapping a second planned rise. This came after our decision to cut fuel duty at Budget 2011 by 1p, abolish the fuel duty escalator and replace it with a fair fuel stabiliser.

"Petrol and diesel will be an average of 10p per litre cheaper than if we had proceeded with the escalator previously announced in 2009."