The latest AA Fuel Price Report shows that, although mid-June's average UK petrol price is almost penny a litre lower than a month ago, it has gone up a third of a penny in the past week.

Petrol in the UK currently averages 136.07p a litre, down 0.86p on mid-May levels. The stock market "flash crash" in oil prices at the start of May took petrol down from a record high of 137.43p on 9 May to 135.75 on 5 June, before prices started going up again.

Diesel car owners enjoyed a greater fall in costs before prices started to rise again. Diesel now averages 139.77p a litre at the pump, down 1.72p on mid-May. Having hit a record of 143.04p a litre in the second week of May, the fall bottomed out at 139.34 on 5 June, before rising 0.43p to where it is now.

The AA also says that drivers have been denied much of the saving that the crash in oil price, from $126 to below $110 could have allowed. It adds that this has short-changed drivers by around 2p a litre or a £1 a tank.

'Without transparency in the oil and fuel markets and a regulator to ensure fair prices, drivers, consumers and the nation are open to being ripped off by whoever wants to make an extra buck,' said Edmund King, the AA's president.