Three cargo vessels have been hit by “unknown projectiles” in the Strait of Hormuz, maritime authorities say, as pressure intensifies on one of the world’s most important shipping lanes.

Traffic through the strait - a vital corridor for oil - has fallen sharply since Israel and the US attacked Iran in late February, sending global energy prices soaring.

Iran said it unleashed another volley of retaliatory attacks across the Gulf on Wednesday, with targets including a major oilfield in Saudi Arabia and drones falling near Dubai International Airport.