Drivers were stung with the return of rising fuel prices in July, new figures show.

Analysis by the RAC found that both petrol and diesel rose by an average of around 1p a litre last month.

The motoring group said this reflects a continuation of "roller coaster" fuel prices as a rise in May was followed by a decline of around 2p a litre in June.

Supermarkets increased their prices the most in July, largely cancelling out the price cuts they introduced just a few weeks earlier.

Across the UK, average unleaded prices at the end of July were 128.8p a litre, while diesel was 131.9p.

There is a high degree of volatility in wholesale fuel prices due to the sharply fluctuating oil price, which started July at just under 77 US dollars a barrel and then fell to 70 US dollars on July 17 before recovering to 74 US dollars at the end of the month.

RAC spokesman Rod Dennis said: "July saw a return to rising prices at the UK's forecourts, following some price cuts in the previous month - the roller coaster effect of rising and falling prices that drivers will have witnessed in recent months is certainly in full swing.

"The volatility of the price of a barrel of oil, and in turn wholesale fuel prices, makes it difficult to determine where prices might go next.

"What is certain, however, is how much more expensive it is to fill up a car this summer compared to last year.

"At the end of July 2018 it cost £7.50 (12%) more to fill a 55-litre unleaded fuel tank compared to the same point in 2017, and £8.77 (14%) more to fill an equivalent diesel."