The price of unleaded petrol was averaging 110.6p per litre yesterday, nearly 16 per cent higher than a year ago, meaning that motorists are paying nearly £7.50 more each time they fill up their car.

The AA’s call comes only a week after Nigel Dodds, Northern Ireland’s finance minister, attacked supermarkets in the province for failing to offer the cheapest fuel to all their customers.

Tesco agreed to uniform petrol pricing in the Highlands two months ago only after Danny Alexander, the MP for Inverness, Nairn, Badenoch and Strathspey, met with the supermarket giant’s chief executive Sir Terry Leahy.

Tesco had been charging 4p per litre more in Inverness than at its store in Elgin.

Esso was the first petrol retailer to introduce a local pricing policy ten years ago when it launched a price watch.

Tesco last night insisted it was a “force for good” for motorists.

A spokesman said that it was easier for Asda to offer a national pricing policy as it only runs 170 forecourts, compared to the 400 managed by Tesco.

He added: “Our position is like most other petrol retailers. We price match locally and customers know we will be the cheapest in the local area.

“I don’t think many people could challenge the fact that we are a force for good in petrol retailing and significantly cheaper than the oil companies.

“Our offer is very different to Asda’s.”

- An official probe into alleged price-fixing between supermarkets and leading consumer brands is focussing on about 20 household items, from Aquafresh toothpaste to Pampers disposable nappies, it emerged yesterday.

If found guilty by the Office of Fair Trading the companies face multi-million pound fines.