A projectile hits a ship's engine room in the Strait of Hormuz, injuring a crew member

The United Kingdom Maritime Trade Operations agency said a ship on passage through the Strait of Hormuz was hit early on Tuesday by what it called an unknown projectile, which damaged the engine room and left one crew member a casualty.

The account reached the agency from the ship's own company security officer, who said the Omani coastguard had moved to assist the rest of the crew. UKMTO did not name the vessel, give its flag or fix the position of the strike.

No environmental damage has been recorded so far, the agency said, and no party has claimed the attack. Authorities are still working out what hit the ship and who sent it.

UKMTO told other vessels crossing the strait to proceed with caution and to pass on anything they see that looks suspicious.

Traffic through the waterway has collapsed since the United States and Israel began their war on Iran on 28 February. Crossings that once ran at more than 130 a day are now counted in single figures.

Iran closed the strait in effect once the war started, has attacked commercial shipping repeatedly since, and says it wants vessels to pay for passage. A memorandum of understanding with Washington, drawn up to lower hostilities and reopen the route, ran out on Monday, while Tehran and Muscat continue a separate set of talks on how navigation should be arranged in future.

Single-figure crossings change what a transit means for the crews still making one. With so few ships moving, a vessel in the strait is no longer one among scores, and the loss of an engine room in that water leaves it dependent on whichever coastguard is nearest.