The RAC says smaller fuel retailers are being fairer to their customers on prices than the big four supermarkets.
The claim came as the RAC revealed the supermarkets raised the price of petrol almost every day for three months.
Data from RAC Fuel Watch shows the supermarkets increased the price of unleaded at the pumps every day since 21 February, except for five days when they stayed the same. The increases were a response to rising wholesale costs, but they have continued on days when other retailers have managed to lower their prices.
During the three-month period the overall UK average price of petrol among all retailers dropped five times, but the supermarkets still increased their prices slightly.
A litre of unleaded petrol now costs 128.35p on average – compared with 119.74p on 21 February – an increase of 8.61p in the three months. At the supermarkets, however, the average increase has been greater – 9.69p – from 115.75p to 125.44p.
RAC fuel spokesman Simon Williams commented: “Our data clearly shows the wholesale price of unleaded has increased dramatically over the last three months which has inevitably led to forecourt prices rising. But it is concerning to see the supermarkets, who many drivers trust to provide them with good value, putting up their prices when other smaller retailers are being fairer with their customers by more closely mirroring movements in the wholesale price.
“While three months of almost daily price rises isn’t an accurate reflection of wholesale price movements, the supermarkets appear to be protecting profits by being overly cautious about not getting caught out by the odd day of lower wholesale prices in what they believe is a consistently rising wholesale market.
“We know oil is in shorter supply globally which is unfortunately pushing up prices for drivers at the pumps in the UK. We can only hope this isn’t going to continue for too much longer, otherwise we will see a return to the five-year high prices of last October when a litre of petrol was nearly 132p and diesel was 137p.”