The Prime Minister is understood to be furious that the 5p cut in fuel duty has not been passed on to customers at many pumps. He has tasked the Department for Transport to draw up proposals to expose the culpable firms.
Transport Secretary Grant Shapps has suggested a government-run forecourt watch or pump watch scheme to name and shame them.
A Downing Street source told the Sunday Telegraph: "Officials are considering mechanisms available to expose those companies that aren't passing on tax benefits to consumers."
A Cabinet minister added: “It’s not up to the Government how much profit business makes. But when we deliver a 5p cut in duty you expect good capitalists to pass it on.”
It comes after motoring body the RAC warned that retailers were taking 2p-per-litre more on average than before the 5p in March. Senior ministers also discussed last week imposing a tax on petrol firms, similar to the windfall tax on oil and gas companies.