Petrol and diesel prices rose by around 3p a litre in December, reaching their highest average level since July 2015.

The 18-month fuel price high is the result of the oil production cuts agreed by OPEC at the end of November.

The RAC Fuel Watch data shows unleaded hit 117.23p a litre and diesel 119.63p at the end of the month, up from 114.24p and 116.56p a litre at the beginning of December.

The increase has been attributed to a near 4p a litre rise in the wholesale cost of both fuels as a result of oil production cuts announced by the Organisation of the Petroleum Exporting Countries at the end of November, which saw the price of a barrel of oil hit $54.86 on 30 December – more than double the low of $26 a barrel recorded in January.

In the course of 2016 unleaded went up 14.5p a litre from 102.99p at the beginning of January and diesel increased 13.64p from 105.99p a litre, although the diesel price went on to reach a low at the end of January of 101.05p, meaning motorists are now paying 18.5p more a litre now.

Increases in December pump prices were seen most at supermarket providers where the average price of a litre of fuel rose 3.34p for petrol and 3.16p for diesel compared to 2.99p and 3.07p nationally across all retailers.

RAC fuel spokesman Simon Williams said: “We are optimistic that prices will not increase by another 3p a litre in January based on what’s going on with oil and wholesale fuel now, but if in the months ahead the barrel price was to get nearer to $60 and the pound was to weaken further then that would be the worst possible combination for motorists.

“Our current forecast for the next two weeks is for petrol to be around the 118p mark and for diesel to go up to around 121p a litre. We should also say that we need the pound not to lose any more value against the dollar as fuel, like oil, is traded in dollars.”