Three commodity vessels transited the Strait of Hormuz on Tuesday, down from four a day earlier and below the 10-day moving average of about 15, preliminary shipping data showed on Wednesday.
The figures may change as some ships typically switch off their transponders during the voyage.
All three vessels, including one Panamax tanker, were exiting the strait, the data from shiptracker Kpler showed at 0200 GMT.
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One ballast liquefied natural gas tanker, Al Mafyar, however reappeared inside the strait on Tuesday, after being last seen outside of the waterway on September 19, according to both Kpler and LSEG data.
The Strait of Hormuz carried a fifth of the world's oil and gas before the US-Iran conflict.
US President Donald Trump said on Tuesday that he could annihilate Iran if there is no deal to end the war, but also suggested an agreement could come soon amid a diplomatic push at the United Nations.
Meanwhile, 22 commodity vessels transited the Bab el-Mandeb Strait on Tuesday, another maritime chokepoint on the southwest tip of Yemen and a vital trade route for oil between the Red Sea and the Gulf of Aden.
The data showed 14 vessels heading towards the Red Sea and 8 towards the Gulf of Aden. They included five Panamax tankers, six Supramax vessels, four Aframax tankers, a Suezmax tanker and a very large crude carrier.
The number compared with an average of around 26 ships using the strait in the past 10 days.
