Mr Williams said that before the drop in wholesale prices, retailers were making a 9p per litre margin, some 3p more than the long-term average. Unleaded is currently 148p a litre on average, super unleaded 160p a litre, and diesel 151p, RAC said. 

Petrol prices reached record highs last month after the price of crude oil hit $85 a barrel. It fell to $73.18 on Friday.

Gordon Balmer, of the Petrol Retailers Association, which represents around two thirds of forecourts, said: “[Our] members mostly buy fuel from their fuel supplier on a weekly lagged basis. Therefore, if they need to order deliveries for this week then they are charged at the average of last week’s product price values. 

“In addition to this, they have been hit by the ‘double whammy’ of reduced sales and rising costs. Members continually monitor prices daily to ensure that they remain competitive with their industry counterparts and continue to provide good value for money.”

Supermarket prices have tended to be lower than other retailers but have reached near-parity. The South East has the highest fuel prices while Northern Ireland has the lowest, according to AA.

Last month the Government scrapped a planned rise to fuel duty that it claimed would have cost drivers an extra £15 every time they filled up.