Petrol and diesel drivers have been urged to shop around when searching for fuel, as they could be overcharged by £9 per tank by some filling stations.
The latest report from the Competition and Markets Authority (CMA) highlighted that higher oil prices caused a rapid increase in fuel costs, rather than a hike in fuel margins.
As part of its latest monitoring report on the road fuel market, the CMA assessed the impact of the Iran war and tensions in the Middle East on fuel prices and margins until the end of March.
Fuel margins, which are the prices at which retailers pay for fuel and the price they sell it at, were broadly unchanged between February and March.
This was similar to the average margins throughout 2025, suggesting that the majority of filling stations across the UK refrained from profiteering.
Despite this, the CMA noted that a minority of retailers were increasing their fuel margins, although it could not determine the "precise drivers" of the hikes.
The regulator confirmed that it would investigate this further for the May monitoring report using data from April.
Tensions across the Middle East caused the price of oil to fluctuate wildly over the last two months, with petrol and diesel drivers bearing the brunt of the price rises.
The CMA identified that some retailers had increased their fuel margins amid soaring costs
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Average prices for petrol and diesel increased by 26p and 50p per litre respectively between February and April 20.
Sarah Cardell, chief executive at the CMA, said: "The conflict in the Middle East has driven sharp increases in road fuel prices, putting real pressure on households and businesses across the UK.
"The CMA's job is to ensure these rises reflect genuine cost pressures - especially given our previous work showing competition among fuel retailers isn't as strong as it should be."
Ms Cardell said the CMA would be increasing its monitoring of the fuel markets, adding that it would "remain vigilant to ensure any fall in costs is passed on quickly to motorists".
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Sarah Cardell, CEO of the CMA, said the organisation would continue to crack down on retailers who were ripping drivers off
| GETTY IMAGESThe CMA emphasised the importance of the Government's Fuel Finder scheme, which was first introduced in February this year.
Drivers are able to see the lowest and most expensive prices for petrol, diesel and premium fuels in their local area and nationwide.
Original forecasts from the Government suggested that drivers using the Fuel Finder tool to shop around could save between one and six pence per litre.
While this was before the Iran war, the CMA suggests that drivers shop around before buying their fuel could save as much as £9 per tank of fuel.
The Fuel Finder scheme could help cut prices by as much as £9 per tank
| PAThe CMA was one of the biggest supporters of the Fuel Finder scheme before it was introduced, as it called for improved transparency for drivers and greater competition among retailers.
"For it to deliver for motorists, all retailers must register and provide accurate data - and we will take enforcement action where they do not," Ms Cardell added.
The latest data from RAC Fuel Watch shows that prices now stand at 156.98p for unleaded petrol and 188.53p for diesel.
While this is a modest drop in cost since prices peaked in mid-April, drivers are still paying some of the highest prices over the last three years.