The RAC has called on retailers to cut diesel pump prices to “fairer levels” that more closely reflect the fuel’s wholesale cost. Analysis by the motorist group found diesel’s wholesale price – the amount that retailers pay for fuel – was just 6p a litre more than petrol last week.

But a litre of diesel at the pumps is being sold at an average of around 168p, while unleaded is just 148p.

The price gap is found across much of Scotland’s forecourts, with a litre of diesel in Edinburgh selling for 169p compared to 147p for unleaded. In Aberdeen, Scotland’s oil-producing energy capital, the cheapest price for diesel sits at 159p with petrol only 139p at the neighbouring pump.

Diesel fuel prices across the UK are not reflecting the recent drop in wholesale costs.

Pump prices Scotland: Fuel retailers accused of charging 20p a litre more for diesel than petrol despite drop in wholesale costs