At least two ships -- both bulk carriers -- have crossed the crucial waterway since Iran and the US said that the vital maritime passage would reopen, and a third is on course to do the same.

Two bulk carriers, including one coming from Iran, crossed on Wednesday morning a few hours after the truce was announced.

A third -- the Botswana-flagged and Chinese-owned Hai Long 1 -- also coming from Iran was almost done transiting the strait on Wednesday afternoon, according to data by maritime monitor MarineTraffic.

The tally only includes vessels navigating with their transponders switched on.

Other boats may have also passed through with their signals switched off.

"The Greek-owned bulk carrier NJ Earth crossed the Strait at 08:44 UTC, while the Liberia-flagged Daytona Beach transited earlier at 06:59 UTC, shortly after departing Bandar Abbas at 05:28 UTC", MarineTraffic said on X Wednesday morning.

The NJ Earth had already crossed the strait heading into the Gulf between Monday and Tuesday before crossing again on Wednesday.

"NJ Earth's transit may be an early sign of movement, but it is still too soon to tell whether this reflects a broader ceasefire-driven reopening or a previously approved exception", Ana Subasic, analyst at MarineTraffic owner Kpler told AFP.

The Greek-owned ship kept its transponder signal on as it transited the strait via an Iranian-approved route near Larak Island, used by most vessels crossing the waterway for the past three weeks.

AFP could not immediately confirm the ship's destination.

The Daytona Beach also passed via the Larak Island route and declared on its transponder that its destination is Fujairah (United Arab Emirates).

Several other ships appeared at 1600 GMT Wednesday to be on course to cross the strait through the same route.

Some shipowners and charterers are preparing to move their vessels stuck in the Gulf, shipping journal Lloyd's List reported on Wednesday morning. It estimates around 800 ships are currently stuck in the Gulf.

Access to the strait was severely restricted by Iran in retaliation against US and Israeli attacks since February 28.

From March 1 to April 7, commodities carriers have made 307 crossings, according to Kpler data, a 95-percent decrease from peacetime traffic.

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