The US military said it struck multiple targets in Iran for the second consecutive day at the direction of President Donald Trump, as a fragile ceasefire came under renewed strain.

In a post on social media, US Central Command said that American military aircraft targeted Iranian military surveillance infrastructure, communication systems, air defence sites, drone storage facilities, and minelayer capabilities in response to an attack on a merchant vessel on Friday.

US Central Command said Iranian forces attacked the oil tanker Kiku with a one-way attack drone.

The tanker was carrying more than two million barrels of crude oil while transiting the Strait of Hormuz.

The US military said Iran had a chance to honor the ceasefire agreement but elected not to when its forces attacked the Kiku. Iranian state television reported explosions in an area just north of the Strait of Hormuz.