A South Korean cargo vessel, HMM Namu, reported an explosion and fire in its engine room while anchored in the strait, though no casualties were reported. It was not immediately clear whether the incident was caused by an attack.
Separately, two vessels were reported hit off the coast of the UAE, while an oil tanker linked to Abu Dhabi National Oil Co (ADNOC) was struck by Iranian drones, according to officials.
The renewed violence has further strained a fragile ceasefire reached in April, with both sides maintaining duelling maritime blockades. Iran has warned that US actions to reopen the strait could violate the truce, while Washington insists it is acting to ensure freedom of navigation.
Oil prices reacted sharply to the escalation, rising more than 5% amid fears of prolonged disruption to global energy supplies.
Diplomatic efforts continue, with talks mediated by Pakistan still under way. Iranian officials said there was no military solution to the crisis, while warning that further escalation could draw the region into a deeper conflict.
The unfolding confrontation underscores the strategic importance of the Strait of Hormuz, a narrow but vital corridor through which a significant share of the world’s oil and gas supplies flows, and highlights how quickly tensions in the region can disrupt global trade and energy markets.
