US President Donald Trump announced on Wednesday he has ordered an investigation into major oil companies, accusing them of failing to reduce pump prices despite sharp drops in crude oil costs.

The move comes as Trump faces mounting criticism over the economic fallout from the Middle East conflict and its impact on American consumers ahead of November’s congressional elections.

“The big Oil Companies are not dropping their price at the pump commensurate with the sharply lower prices they are paying for Oil,” Trump wrote on Truth Social. “Those prices are dropping like a rock! In other words, customers are being ‘gouged’.”

Global petroleum prices surged after Iran blocked oil shipments through the Strait of Hormuz in February, following US-Israeli strikes on Iranian targets. The strait is a critical chokepoint for global oil supplies.

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Tehran and Washington have since reached an initial agreement allowing tanker traffic to resume through the waterway, though disputes over Iran’s nuclear programme remain unresolved.

Fuel prices have declined since the deal was announced but remain above pre-war levels. According to the AAA motor club, regular gasoline averaged $3.93 per gallon (3.8 litres – R65,22) on Tuesday.

The president had repeatedly predicted fuel prices would “come down like a rock” after the conflict ended. However, economists expect oil prices will take months to return to pre-war levels.

Gasoline costs are a politically sensitive issue in the United States, where most Americans rely on petrol-powered vehicles for transport. Trump has faced backlash from citizens who accuse him of spending billions in taxpayer funds on the Middle East war whilst oil prices and inflation remain elevated domestically.

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