A trickle of ships has passed the Strait of Hormuz over the past two days, though the US military said Wednesday that its blockade of vessels going to or from Iranian ports had been fully implemented during the first 48 hours.

On Thursday, two very large crude carriers (VLCC), the RHN and the Alicia, were near Iran's coast in the Gulf having passed the strait after the US imposed its blockade on Monday, according to data from maritime tracking firm Kpler.

US regional command CENTCOM said more than 10,000 personnel were deployed for the blockade "against vessels of all nations entering or departing Iranian ports and coastal areas".

The two supertankers had previously broadcast their destinations as Iraq but changed them to "for order" as they passed the strait, Kpler data showed.

A third VLCC, the Agios Fanouris I, and a liquid petroleum gas tanker, the G Summer, were also in the Gulf after crossing the strait during the blockade and reported their destinations as Iraq, the data showed.

Two other vessels, the container ship Zaynar 2 and empty general cargo ship Neshat, also crossed the strait on Wednesday and Thursday and were detected near the Iranian port of Bandar Abbas, according to Kpler's tracking platform MarineTraffic.