A row has broken out over alleged profiteering at Britain's petrol pumps.
Motorists are feeling the pain in their pockets, as fuel prices jump on an almost-daily basis.
Now the head of the country's fastest-growing petrol forecourt operator has accused supermarkets of profiteering.
Darren Briggs, chief executive of Ascona Group, has claimed that companies such as Tesco, Sainsbury's, Morrisons and Asda were failing to pass on savings to drivers despite buying in fuel more cheaply than independent rivals.
But Asda hit back, saying it is the "price leader" and was the first forecourt operator to pass on cuts to fuel duty.
Mr Briggs welcomed a competition inquiry into forecourt pricing, yet criticised Boris Johnson for making petrol station operators a "scapegoat" of the ongoing energy crisis.
He said that the amount of verbal abuse directed towards his staff had risen since the Prime Minister pledged to crack down on "rip-off" prices at the pumps.
Wholesale price lag
The Telegraph explained that the wholesale price supermarkets pay is typically based on a lag of up to three weeks, allowing them to bolster profit margins at a time when oil prices are rising sharply. This compares with independent operators, most of which pay for fuel based on the previous week's average price. Around a quarter are forced to pay the spot price on the day the fuel is delivered.
In a rising market, this means independent operators must increase their prices more quickly - giving supermarkets the chance to make bigger profits if they follow suit, Mr Briggs said.
The criticism of supermarkets came as the Competition and Markets Authority confirmed it would conduct a "short and focused review" of the fuel market in response to Kwasi Kwarteng, the Business Secretary, asking the body to investigate if duty cuts were being passed on to customers.
Prices at the pumps have hit fresh highs, prompting calls for the Government to reduce duty further to help households that are already grappling with the cost of living crisis.
Simon Williams, RAC fuel spokesman, said: "The speed and scale of the increase is staggering with unleaded going up 7p in a week and diesel by nearly 6p.
"This must surely put more pressure on the Government to take action to ensure drivers don't endure a summer of discontent at the pumps."
The big four supermarkets - Tesco, Sainsbury's, Morrisons and Asda - enjoy a dominant position in the UK fuel market, selling more than 43% of the fuel by volume.
A spokesman for Asda told the Telegraph: "Asda is the price leader in the supermarket fuel sector and despite significant increases in wholesale fuel costs our average petrol price today is 8p per litre cheaper than independent operators. We were also the first retailer to pass on the cut in fuel duty and will continue to do all we can to offer customers the lowest prices at the pumps."
Hopes that fuel prices could fall if there is a drop in the oil price continue to be dashed.
Brent crude futures were holding steady this morning at $121.14 a barrel.
FTSE 100
The UK's top share index, the FTSE 100, was up 45 points at 7,233 shortly after opening this morning, following yesterday's 18-point loss.
Companies reporting today
- Full-year results: JPMorgan European Discovery Trust
- Trading updates: Whitbread, WH Smith