President Donald Trump said Wednesday that he had instructed the Department of Justice to immediately probe oil companies for not lowering gas prices at the pump in line with falling costs, accusing them of “gouging” consumers.

Trump did not name any companies in his late-night message on TruthSocial, which was posted shortly after midnight.

“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. “Those prices are dropping like a rock! In other words, customers are being ‘gouged.’ I have instructed the DOJ to immediately start looking into this. Gasoline prices better start going down a lot faster than what I’m seeing!” he added.

There was no immediate confirmation of any probe from The White House or the Department of Justice.

Trump’s war in Iran and Tehran’s subsequent closure of the Strait of Hormuz rocked global markets and sent energy prices soaring, resulting in higher gas prices for Americans at the pump.

That has translated into concerns that consumers may punish Republicans in November’s midterm elections.

But prices have eased in recent weeks amid peace talks, and more relief followed the news of an interim deal that would include reopening the crucial waterway, through which one-fifth of global oil supply is moved.