The cost of unleaded petrol and diesel crept up again in September, as a result of rising world oil prices putting upward pressure on the wholesale cost of both fuels, new data from RAC Fuel Watch shows.

Diesel averaged 113.34p per litre at the end of September, the highest average price since August 2015, and up 0.42p on the price at the beginning of the month.

The average cost of a litre of petrol meanwhile, ended the month at 112.07p, up 0.48p on the average price at the start of September and just short of the 2016 high price of 112.33p.

Supermarket prices both rose faster than average prices, with unleaded up 1.1p and diesel up 0.71p

The price of a barrel of oil, the biggest variable affecting UK fuel prices, went up 8%, or $3.45, through September finishing the month at $48.35 a barrel and a little way off the 2016 high price of $50.73 that occurred in early June.

The price rises mean that it now costs on average £61.63 to fill up an average-sized 55-litre petrol family hatchback, which is just over £5 more per fill-up than at the start of the year.

To fill an equivalent diesel vehicle costs £62.34, around £4 more than it did in January. For a light commercial diesel vehicle with an 80-litre tank, it now costs £90.67 to fill from empty, up £5.88 since the start of the year.

RAC fuel spokesman Simon Williams said: “While there have been no shocks at the pumps lately, recent reports that OPEC – the organisation responsible for producing 40% of the world’s oil – has agreed there is to be a cut in oil production is having the effect of nudging oil prices up closer to the $50 a barrel mark.

“A higher oil price, combined with a weakening pound, is forcing up wholesale fuel prices: the wholesale price of diesel is now nearly 9p higher than it was at the start of August, and petrol 7.4p higher. The effect of this to date has been gradually rising pump prices.

“While we don’t envisage an immediate hike in prices in October, a lot depends on how markets react to the recent news of the first production cut by OPEC nations since 2008, which marks a major move away from the organisation’s long-term over-supply strategy. The announcement has already caused oil prices to jump a little, but until more specific details are available it is difficult to predict what the longer term outlook on pump prices, and therefore impact on motorists, will be.

“The new chancellor’s first Autumn Statement also looms next month, and the RAC hopes that he sees sense in committing to not increase fuel duty for the remainder of the Parliament – certainly compared to his predecessor’s track record on fuel duty, the new chancellor has a lot to live up to.”

Regional fuel price variation                                                      

The South East of England is currently the most expensive place to buy petrol in the UK, with average prices there standing at 112.62p per litre. East Anglia is selling the priciest diesel, at an average of 113.96p per litre. This region also recorded the biggest price rises through September, with petrol up 0.84p per litre and diesel up 0.61p per litre.

Northern Ireland witnessed the most modest increase in diesel prices, up just 0.12p to 112.03p per litre, and was the only part of the UK to see average petrol prices fall – by a marginal 0.02p to 110.76p per litre.

Regional average diesel pump prices

Diesel – pence per litre

1/9/16

29/9/16

Change

East Anglia

113.35

113.96

+0.61

East Midlands

112.81

113.24

+0.43

North

112.57

112.85

+0.28

North West

112.60

112.94

+0.34

Northern Ireland

111.91

112.03

+0.12

Scotland

112.92

113.40

+0.48

South East

113.30

113.86

+0.56

South West

113.22

113.54

+0.32

Wales

112.57

112.87

+0.30

West Midlands

112.96

113.39

+0.43

Yorkshire And Humber

112.50

112.78

+0.28

Regional average unleaded pump prices

Petrol – pence per litre

1/9/16

29/9/16

Change

East Anglia

111.67

112.51

0.84

Wales

110.95

111.61

0.66

South East

111.98

112.62

0.64

Scotland

111.11

111.74

0.63

North

110.99

111.48

0.49

West Midlands

111.84

112.30

0.46

East Midlands

111.60

112.01

0.41

South West

111.76

112.04

0.28

Yorkshire And Humber

111.26

111.42

0.16

North West

111.54

111.69

0.15

Northern Ireland

110.78

110.76

-0.02