President Donald Trump said on Thursday Iran should not charge fees to tankers going through the Strait of Hormuz, which has been blockaded since the start of the Iran war, causing the worst disruption to global energy supplies in history.
"There are reports that Iran is charging fees to tankers going through the Hormuz Strait," Trump wrote on social media.
"They better not be and, if they are, they better stop now."
Media reports have suggested Iran might want to charge a toll for ships passing through. Western leaders have pushed back on the idea of paying any such fees.
Iran will demand toll payments in cryptocurrency to retain control over Hormuz during a two-week ceasefire with the US, the Financial Times quoted Hamid Hosseini, a spokesperson for Iran's Oil, Gas and Petrochemical Products Exporters' Union, as saying on Wednesday.
In a separate post, without elaborating, Trump said, "you'll see Oil start flowing, with or without the help of Iran."
The US and Israel attacked Iran on February 28. Iran responded with its own strikes on Israel and Persian Gulf states with US bases. The war has raised oil prices and shaken global markets.
US-Israeli strikes on Iran and Israeli attacks on Lebanon have killed thousands and displaced millions.
Trump announced a ceasefire with Iran on Tuesday, after having previously threatened to destroy Iran's entire civilisation.
Ship traffic through the strait stood at well below 10 per cent of normal volumes on Thursday despite the fragile ceasefire as Tehran asserted its control by warning ships to keep to its territorial waters while doing so.
The war brought traffic through the strait, a chokepoint for about 20 per cent of global oil and liquefied natural gas shipments, close to a standstill.
(Reporting by Kanishka Singh and Bhargav Acharya; Editing by Bill Berkrot)