Tankers moving oil through the Strait of Hormuz face a sharply higher risk of attack after Iran issued fresh warnings that it will block routes it has not authorised, according to a Reuters report carried by the Daily Mirror.

Last week saw the largest number of attacks on tankers in the waterway since the war began, and the number of vessels attempting the passage fell to its lowest in more than two months.

The warning

Iran has told regional countries that any attempt to open new routes for oil exports would be treated as a hostile act, a senior regional official close to Tehran told Reuters. The official said this was part of a plan agreed by both Iran’s political leadership and the Revolutionary Guards.

A senior regional diplomat briefed by Tehran put it more directly:

“Iran has absolutely no intention of allowing control of the Strait of Hormuz to slip from its hands, and has plans ready to block routes that some regional countries have for exporting oil.”

“This could involve missile and drone attacks on ships, or sending boats to scare ships away. It plans to continue this policy of fear and threats.”

In recent months Gulf producers have been pushing cargoes through channels hugging the Omani side of the strait, then transferring oil in open water in the Gulf of Oman under US aerial cover — the workaround Tehran now appears to be targeting.

The strike off Qatar

In the most recent incident, projectiles hit a tanker inside the Gulf north of Qatar’s Madinat ash Shamal. The British navy agency UKMTO put the position about 51 nautical miles off the Qatari coast; Al Jazeera reports it as 94 kilometres — the same distance.

Maritime security sources identified the vessel to Reuters as the Acers, an Antigua and Barbuda-flagged chemical tanker, and said its crew sustained minor injuries. Al Jazeera’s account differs here: it reports that “a number of casualties” were reported and that UKMTO did not say how many people were killed or injured. The operator, listed in shipping databases as Valvoria Shipping, could not be reached for comment.

Clearwater Dynamics, a subsidiary of the maritime risk group Pole Star Global, said in a report on Thursday that the strike “raises the prospect of a wider combat area affecting approaches to Qatar, Bahrain, Saudi Arabia, Kuwait and Iraq.”

Al Jazeera counts nine attacks on tankers in the strait during October — half the September total for the waterway and the Gulf combined. Iran effectively closed the strait in retaliation for US-Israeli attacks after the war began on 28 February.

The wider cost

Jakob Larsen, chief safety and security officer at the shipping association BIMCO, said shipowners are pulling back: “The recent spate of Iranian attacks seems to have dampened the appetite of shipowners to sail through the Strait. The Iranian threat appears to have increased.”

US President Donald Trump is weighing further steps, including whether to escalate strikes before or after November’s midterm elections, while maintaining a naval blockade intended to force Tehran into a deal. Reuters puts the war’s cost at US$3 billion a month.

Governments and energy companies have been drawing down stockpiles to cushion a market already disrupted by the war in Ukraine, and industry executives at a London forum this week said accessible storage is running low — leaving prices more exposed. Maersk said on Thursday it was raising its emergency fuel surcharge on inland transport in the UK and Ireland.

Why it matters here

Sri Lanka imports all of its crude and refined fuel, and freight and insurance on Gulf cargoes have been the main channel through which this war reaches local pump prices. In September, Gulf-to-Asia freight was running at $30 a barrel against $6 before the war, with marine insurance fifty times its pre-war level.

Separately, the Foreign Ministry told Tehran this week that Sri Lanka will not supply the roughly 20 Iranian vessels stranded off the island, citing exposure to US secondary sanctions.

Not reported: neither filing names the routes Iran considers unauthorised, nor which regional countries’ export channels it is threatening. No Iranian government statement is quoted directly — the warnings reach Reuters through an official and a diplomat, both unnamed. Neither account says whether the Acers was using one of the disputed routes.