Oil prices hit a four-year high, then fell back slightly, before Mojtaba Khamenei issued a written message read out on state television declaring that Iran was now in the driver's seat in the crisis.

"Today, two months after the largest military deployment and aggression by the world's bullies in the region, and the United States' disgraceful defeat in its plans, a new chapter is unfolding for the Persian Gulf and the Strait of Hormuz," he said, hailing Iran's control over shipping in the strait.

He went on to predict a bright future for the Gulf without the United States, saying those who interfere in the region from afar "have no place there except at the bottom of its waters".

Khamenei was wounded in the initial US-Israeli strikes that killed his father Ali Khamenei, and has not been seen in public since being named his successor as supreme leader last month.

The United States imposed a blockade on Iran's ports two weeks ago, while the Islamic republic has maintained its stranglehold over the strategic Strait of Hormuz since the start of the Middle East war at the end of February.

Now Washington is seeking to set up an international coalition comprising allied states and shipping firms to coordinate safe passage through Hormuz, a State Department official told AFP -- while maintaining its blockade of ships serving Iran.

And Iran's parliament speaker Mohammad Bagher Ghalibaf said control of Hormuz would allow Tehran to "provide itself and its neighbours with the precious blessing of a future free from American presence and interference".

Trump is expected to receive a briefing on Thursday on new plans for potential military action in Iran from Admiral Brad Cooper, the head of US Central Command, two sources with knowledge of US planning told news site Axios.

Israeli Defence Minister Israel Katz warned, meanwhile, that it was "possible that we may soon have to act again" against Iran to achieve the war's objectives.

But the commander of the Iranian Revolutionary Guards aerospace force, Majid Mousavi, said that even a "short and tactical" enemy operation would be met with "with painful, prolonged, and extensive strikes".

- 'Choking' -

This week Trump has reportedly told oil executives and national security officials to prepare for a long US blockade designed to force Tehran to surrender its nuclear programme, and, speaking to Axios, said: "They are choking like a stuffed pig."

US Central Command said Wednesday in a social media post that it had reached a "significant milestone after successfully redirecting the 42nd commercial vessel attempting to violate the blockade".

Iranian President Masoud Pezeshkian said that the blockade of his country's ports was effectively an "extension of military operations" by Washington, in spite of the ongoing ceasefire.

"Continuation of this oppressive approach is intolerable," he added.

Oil prices struck a four-year high on Thursday. International benchmark Brent crude soared more than seven percent to $126 a barrel, but then eased in afternoon trading in London.

UN chief Antonio Guterres said the closure of Hormuz was "strangling the global economy" and International Energy Agency chief Fatih Birol told a meeting at his Paris headquarters: "The world is facing the biggest energy crisis in history."

Trump faces domestic political pressure to end the war, which is unpopular even with much of his base, and has increased costs for American consumers and unnerved US allies.

Iran's economy is also suffering and the rial has fallen to historic lows against the dollar.

- 'Heartbreaking' -

Tehran residents speaking to AFP journalists in Paris reported a sense of despair that the Islamic republic government was clinging to power and the negotiations have stalled.

"Without pressure from the US, imagining the future with this regime is very frightening, and the experience of war is terrifying as well," one 28-year-old IT worker told AFP journalists in Paris via messaging app from the Iranian capital.

"From the Islamic Republic still being in place to the innocent people whose lives were destroyed in this war, everything is so disappointing."

Iran proposed easing its chokehold over the Strait of Hormuz if Washington lifted its blockade and broader negotiations took place. But the Trump administration has insisted that Iran's nuclear programme be on the table.

Violence has continued on the war's Lebanese front, despite a recently extended ceasefire between Israel and Hezbollah.

Israeli strikes on southern Lebanon killed at least 15 people, the health ministry said Thursday, while the Lebanese army said a separate strike on a home in the south killed a soldier and multiple members of his family.

Lebanese President Joseph Aoun denounced what he called "continuing Israeli violations" of the truce, saying "pressure must be exerted" on it to compel it to stop.

The Israeli military said Thursday that another soldier had been killed in Lebanon's south -- the 17th since the campaign there began.

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