A tanker was attacked on Friday while leaving the Gulf via the Strait of Hormuz, causing a fire but no casualties, a British maritime agency said.
The vessel was hit by an "unknown projectile" in the strategic waterway, "resulting in a small fire and blackout onboard." But it said "the fire has since been extinguished and the vessel is underway" and "there are no reported casualties or environmental impact."
The agency said authorities were investigating the incident.
The Strait of Hormuz, through which a fifth of the world's oil and LNG passed before the US and Israel launched strikes against Iran in late February and sparked the Middle East war, is still at the heart of the conflict.
Tehran has been blocking the passage of commercial ships, firing on vessels it accuses of unauthorised crossings.
Washington responded with a counterblockade of Iranian ports in an effort to prevent Tehran from exporting its oil.
Agence France-Presse