Iran will allow no more than 15 vessels a day to pass through the Strait of Hormuz under the ceasefire agreement it agreed with the United States, Russia's state TASS news agency quoted an unnamed senior Iranian source as saying on Thursday.

The Strait, a strip of water only 21 miles wide between Iran and Oman, provides passage from the Gulf to the Indian Ocean and is the main route for about a fifth of world oil supplies and other vital goods including fertilizers.

It has been largely shut by Iran since the start of the conflict at the end of February, leading to a surge in global oil prices.