Four commodity vessels transited the key waterway of the Strait of Hormuz on Thursday, down from nine a day earlier and well below the 10-day average tally of about 15, preliminary shipping data showed.
Two medium-range tankers, a Kamsarmax carrier and a Handysize vessel made up the figure, Kpler data showed by 0455 GMT on Friday.
The figure excludes vessels that might have crossed the strait with their Automatic Identification System transponders turned off to avoid detection.
Oil prices were heading on Friday for their steepest weekly gain since mid-July, as rising tension and renewed U.S.-Iran hostilities heightened concerns over Middle East supply risks.
So far this week, Kpler data showed only two very large crude carriers crossed the strait.
Before the Iran war started on February 28, about 125 large commercial vessels went through the strait each day, including tankers, gas carriers, bulkers and container vessels, making up a fifth of global daily crude oil and liquefied natural gas supply.
A U.S. blockade of Iran-related shipping has halted Iranian crude oil exports since it was reimposed in mid-July.
During the war, daily observed oil and product exit volumes have ranged mostly between 4 million and 6 million barrels per day, except for a rise to close to pre-war level during the brief interim deal struck by Iran and the United States, Rystad Energy chief economist Claudio Galimberti said on Thursday.
“There is little that the United States and Iran currently agree on,” he told an energy summit in Singapore.
“Therefore, we expect flows to remain very low until November, as the economic costs associated with a lasting disruption continue to weigh.”
At the Bab el-Mandeb strait on the Red Sea, 22 commodity vessels crossed on Thursday, down from 31 the day before and below the 10-day average tally of 24, Kpler data showed.
(Reporting by Siyi Liu in Singapore; Editing by Thomas Derpinghaus and Clarence Fernandez)