Around a fifth of global crude oil and liquefied natural gas (LNG) passes through the waterway in peacetime.

The war erupted on February 28 when the United States and Israel began bombing Iran, prompting Tehran to retaliate with strikes across the region and restrict access to the strait.

- Tanker hit in Qatar waters -

A tanker leased to Qatar's state-owned energy company was struck by an Iranian missile in the Gulf country's territorial waters, officials there said Wednesday.

QatarEnergy confirmed the oil tanker Aqua 1 had been targeted but that there had been "no impact on the environment as a result". Meanwhile, 21 crew members were evacuated without any casualties, Qatar said.

British marine security agency UK Maritime Trade Operations (UKMTO) said the vessel had been struck by "two projectiles" north of Ras Laffan, the world's largest LNG hub.

It noted "one projectile caused a fire, which was extinguished, and another "remains unexploded within the vessel's engine room".

It means 27 commercial ships, including 13 tankers, have been attacked or reported incidents since March 1 in the Gulf, the Strait of Hormuz, or the Gulf of Oman, according to UKMTO reporting.

- Hormuz summit -

Britain will hold a meeting of around 35 countries later this week to discuss how to reopen the strategic waterway, Prime Minister Keir Starmer said.

The meeting will "assess all viable diplomatic and political measures that we can take to restore freedom of navigation, guarantee the safety of trapped ships and seafarers and resume the movement of vital commodities", he said.

Foreign Secretary Yvette Cooper will host the discussions, Starmer said, but the date and format were not announced.

- Handful of crossings -

Just six vessels crossed the strait on Tuesday and early Wednesday, according to maritime intelligence firm Kpler.

From March 1 to April 1, as of 1100 GMT, commodities carriers made 214 crossings, according to Kpler data.

Of these, 131 were by oil tankers and gas carriers and most were travelling east out of the strait.

The channel in peacetime sees around 120 daily transits, according to shipping industry intelligence site Lloyd's List.

- 2,000 ships in Gulf -

Bloomberg data showed Wednesday that 2,190 vessels sent transponder signals in the Gulf west of the Strait of Hormuz over the past day.

Of those, 327 were oil and gas vessels, including 12 very large gas carriers and 50 very large crude carriers.

- Iran-approved route -

Recent crossings appeared to have mainly used a route apparently approved by Iran around Larak Island just off the country's coast.

Leading shipping journal Lloyd's List on Tuesday estimated at least 48 ships had used it since last week, the majority with links to Iran.

The Revolutionary Guards has said the route was closed to vessels travelling to and from ports linked to Iran's "enemies".

- 46% sanctioned ships -

Since the war started, 46 percent of the crossings have been by ships under US, EU or UK sanctions, according to an AFP analysis of passage data.

Of the crossings by oil and gas tankers, 63 percent were by vessels under sanctions.