Supermarkets are on average charging 3.3ppl less for petrol and 3.6plp less for diesel than their rivals, according to the latest AA Fuel Price Report.

It says only Jet has closed the price gap on the big four superstores, trailing them by around 1.8ppl on petrol by charging below average pump prices.

Since mid-May, the UK’s average price of petrol has gone up another 2.4ppl to 111.58ppl, while diesel now averages 111.80ppl, up 2.7ppl.

The report also highlighted the national variation across the UK, with average petrol and diesel prices varying by as much as 2.5ppl.

In Northern Ireland, where supermarket pump prices for both main fuels were below 108ppl in some towns last week, petrol averaged the lowest price in the country at 110.5ppl with diesel at 110.0ppl.

In the South East, petrol was most expensive with an average of 112.0ppl, and diesel was 112.5ppl.

AA president Edmund King commented: “This time last year pump prices were at a pivotal point: fear of a duty increase in the chancellor’s post-election budget, after a 10ppl surge in petrol prices since February. On the other hand, a 5ppl fuel duty rebate for remote rural fuel stations was doubling business for some.”

“What we didn’t know was that pump prices were about to start the decline that would lead to a collapse and £1 a litre on forecourts.”

“This June, drivers have suffered another 10ppl leap in petrol prices since the end of January. The doubling in the price of oil seems to have reached a plateau of around $50 a barrel. The burning question is what happens next?”