Three of the big four supermarkets have been accused of putting up their fuel prices well above the increase on the wholesale market in the latest monthly RAC Fuel Watch survey.

The average price of fuel at the pumps in the UK rose by 2ppl in December, and this was due to the actions of the three supermarket chains, according to the RAC.

The average price of petrol went up from 114.39ppl to 116.46ppl (2.07ppl) and diesel increased from 117.72ppl to 120ppl (2.28ppl) over the course of the month. On the wholesale market a litre of unleaded went up by just 1.28p from 85.76p to 87.04p. Diesel rose by 1.11p from 88.33p to 89.44p.

Of the four big supermarkets fuel retailers however, Morrisons, Sainsbury’s and Tesco all raised their forecourt prices by an average of 3ppl, with only Asda matching the wholesale market price increase by raising its prices by around 1.5ppl.

This meant that Asda was selling the cheapest supermarket petrol and diesel at the close of December. A litre of unleaded cost 110.11p (up 1.31p from 108.8p) and diesel was 113.4p (up 1.52p from 111.88p).

RAC fuel spokesman Simon Williams said: “It’s very disappointing to see some of our biggest fuel retailers putting up their prices over and above the increases seen on the wholesale market. There’s a definite feeling that they have been trying to protect themselves for what was to come in terms of further coronavirus restrictions.

“While wholesale prices went up very slightly in December our data shows there should be scope to lower forecourt prices rather than put them up. Retailers will no doubt argue that the pandemic is leading to drivers filling up far less so their ‘per litre’ profits are considerably down, and Monday’s announcement of another lockdown will be treated as justification for their decision not to pass savings on at the pumps. Unfortunately, those who still need to fill up regularly are having to pay more than they should be as, by our calculations, both fuels should actually come down by 3p a litre in the next fortnight.

“That said, the oil market is still being adversely impacted by Covid travel restrictions so it may be the case that drivers are paying less for their fuel than they might otherwise be. And, even though a barrel of oil was above $50 for half of December – something that we haven’t seen since March last year – the wholesale price didn’t shoot up due to the pound gaining 2% on the dollar.

“Interestingly, retailers have adjusted their margins and are now making roughly the same on petrol as diesel whereas normally they take a larger margin on a litre of diesel. For example, in September the margin on diesel was 4.5p more than petrol at an average of nearly 11.5p (11.4p) a litre compared to around 7p (6.85p).

“As and when life begins to become more normal as a result of the Covid vaccination programme the price we pay for fuel will inevitably go back up again. A year ago, a litre of unleaded set drivers back 127p and diesel 132p, which is 10p and 12p cheaper, respectively, than today.”