Iran's shipping association has called for a new doctrine governing the Strait of Hormuz, saying Tehran should formally charge extra-regional powers for the cost of maintaining security in the waterway and block passage to vessels from countries that have attacked or supported attacks on Iran.

Masoud Polmeh, secretary of Iran's Shipping and Related Services Association, told Fars News on March 31 that the strait's annual logistics financial turnover alone exceeded $170bn, a figure he said underlined the leverage Tehran now held.

Polmeh said Iran had already begun implementing a selective passage policy, blocking tankers and commercial fleets from countries that had taken military action against Iran or supported such action, while facilitating transit for vessels from Iraq, Pakistan, India, Malaysia and Turkey.

He outlined the scale of global dependence on the waterway, saying between 20% and 40% of the world's fossil energy passed through the strait, including 20% of global oil and 30% of global gas.

Up to 60% of the world's petrochemical products and urea fertiliser originated in the region, and the five southern Gulf states controlled at least $1.6 trillion in annual non-energy trade, equivalent to one fifth of global commerce.

Polmeh criticised the US for violating international law and endangering commercial shipping through its bases in the southern Persian Gulf, and said Iran could no longer remain silent in the face of unilateral violations.

"Security in the Strait of Hormuz is tied to the security of the country with the longest coastline along it. If Iran's economic security is not maintained, insecurity will spread to the entire world," Polmeh said.

He called on Iran to define clear boundaries for the strait and demand payment for maintaining safe passage, saying existing international rules had been rendered meaningless by the actions of self-proclaimed major powers.

"Iran must define clear limits for ensuring security and safe transit along this route and demand the costs of maintaining this boundary," he said.

Polmeh also noted that much of Iran's container trade had previously been transhipped through Dubai's Jebel Ali port, but that this flow had now been disrupted by the war.

Iran could earn up to $60bn annually by levying transit tariffs on energy and goods passing through the Strait of Hormuz, an Iranian economist has said, as data shows Tehran is already reaping a wartime oil windfall as the only major Gulf exporter still moving crude freely through the waterway.

On the same day, Hossein Raghfar, a university professor and economic analyst, told Tasnim News Agency that Iran's armed forces had secured a strategic and economic advantage by controlling the strait that few had anticipated before the war began.

"Today the position of the sanctioner and the sanctioned has been reversed. A very powerful tool is now in the hands of our country, and that is control of the Strait of Hormuz," Raghfar said.

The scale of Iran's current oil earnings underlines the point. Iran is estimated to be generating around $139mn per day from sales of its flagship Iranian Light crude in March, up from approximately $115mn per day in February, according to Tankertrackers.com export data.

Exports have remained close to pre-war levels of around 1.6mn barrels per day, with tankers continuing to load at Kharg Island and transit the strait while other Gulf producers face severe disruption.

Iran's crude is also commanding significantly better prices. The discount of Iranian Light to Brent has narrowed from over $10 per barrel before the war to just $2.10 per barrel, while Brent itself has surged above $100 per barrel and reached $126 per barrel at its peak.