Iran allowed 10 oil tankers to pass through the strategic Strait of Hormuz as a "present" to show it was serious about negotiations to end the war, US President Donald Trump said Thursday.

Trump was referring to cryptic comments he made two days earlier about a "gift" from Tehran that involved the flow of oil and gas through the waterway, a key chokepoint for the global energy trade.

Iranian forces have effectively slowed shipping through the strait to a trickle during the Middle East war, which began nearly four weeks ago.

"They said 'to show you the fact that we're real and solid and we're there, we're going to let you have eight boats of oil,'" Trump told reporters in his first cabinet meeting since the conflict started.

The tankers were believed to be Pakistani-flagged, Trump said, adding that he had seen news reports that they had passed the strait.

"And, I said, 'well, I guess we're dealing with the right people'. And actually, they then apologized for something they said, and they said, 'We're going to send two more boats.'"

Before giving his account to reporters, Trump first checked with his Middle East negotiator Steve Witkoff at the cabinet table, saying: "Steve, can I reveal the present?"

The US president did not provide any further details.

Data from marine intelligence firm Kpler shows that six laden oil tankers and five loaded gas carriers have transited the Gulf since Monday, but there was no independent confirmation these were the ones cited by Trump.

Of these vessels, three oil tankers and two gas carriers are currently subject to US sanctions related to Iran. Based on tracking signals, two of the six oil tankers appear to be heading toward China, while one is bound for Thailand.

Among the gas carriers, one is en route to Singapore, and another has already arrived in India. For the remaining six vessels, their destinations cannot be determined from the available data.