US President Donald Trump has said he has ordered an investigation into major energy companies, accusing them of "gouging" drivers by failing to cut fuel prices after wholesale oil costs fell in global markets.

Trump wrote on social media that he had expected to see petrol prices fall "a lot faster than what I'm seeing". He did not name any oil firms in the post.

His remarks come after wholesale oil prices fell from peaks seen during the US-Israel war with Iran, but remain higher than before the conflict started.

The American Petroleum Institute (API), which represents the oil and gas industry in the US, said petrol prices "don't move in lockstep with crude oil".

Trump said in the post on Wednesday: "The big Oil Companies are not dropping their price at the pump commensurate with the sharply lower prices they are paying for Oil.

"Those prices are dropping like a rock! In other words, customers are being 'gouged.'"

He added that he had ordered the Department of Justice (DOJ) to "immediately start looking into this".

"The price of fuel is not only a national security issue, but it also impacts the wallet of every American. We will always commit to ensuring affordability in this nation," a DOJ spokesperson told the BBC without confirming whether an investigation had been launched.

A White House spokesperson said: "President Trump was clear all along that there would be short-term, temporary disruptions to energy markets, and that oil and gas prices will quickly fall as soon as the Iran situation is resolved.

"President Trump has a proven track record of bringing gas prices to historic lows, and the Administration continues to be laser-focused on delivering economic relief for the American people."

In response to Trump's comments, the API's spokesperson Bethany Williams said: "Our industry shares the goal of delivering relief at the pump and restoring stability to global energy markets."

She added that the conflict is "still affecting supply, refining and inventories".

Oil prices shot up after Iran responded to US-Israeli strikes on 28 February by effectively shutting the critical Strait of Hormuz waterway, severely disrupting shipments of oil and gas and causing energy prices to soar.

Brent crude, the global wholesale oil benchmark, reached almost $120 (£91) a barrel in May as the war continued.

But prices have fallen since as peace talks have progressed. On Wednesday, Brent dropped below $74 a barrel, but it is still above the roughly $70 a barrel mark it was at before the conflict.

It is a similar picture with the US wholesale oil benchmark, WTI crude, which dipped to $70 a barrel on Wednesday but remains higher than before the war when it traded at around $60 a barrel.

Meanwhile, the average price of regular gasoline in the US has fallen to about $3.93 per gallon after topping $4 per gallon in April, its highest level since 2022, but remains well above pre-war levels.

Trump's comments come after UK oil firms faced similar accusations of unfairly hiking petrol prices following the start of the Iran war.

However, the UK competition regulator said in May there was no widespread evidence of this, adding that average profit margins were "broadly unchanged" between February and March.