"At this very moment, our oil tanker is passing through the Strait of Hormuz," Foreign Minister Cho Hyun told lawmakers at the National Assembly in Seoul.

"It is the first South Korea-flagged ship to pass through the Strait of Hormuz since the Iran war began," a foreign ministry official told AFP.

Ship-tracking site MarineTraffic showed the South Korea-flagged tanker Universal Winner on the eastern side of the Strait of Hormuz near the entrance to the Gulf of Oman, bound for the southeastern South Korean city of Ulsan after departing Kuwait's Mina Al Ahmadi port.

The passage comes weeks after a South Korean-operated vessel was hit by airborne objects near the Strait of Hormuz, heightening concerns in Seoul over the safety of South Korean shipping in the region.

HMM Namu was struck by "two unidentified aircraft" on May 4, hitting the outer plate of the vessel's port-side ballast tank near the stern and causing a fire in the engine room.

The Panama-flagged cargo vessel, operated by South Korean shipping firm HMM Co., had arrived in Dubai after the incident for investigation.

Tehran has denied responsibility, with its embassy in Seoul posting a statement on its website in the days following the attack, saying it "firmly rejects and categorically denies any allegations regarding the involvement" of its forces.

Seoul strongly condemned the attack and said it hoped to identify those behind it through a thorough investigation.

South Korea, Asia's fourth-largest economy, relies heavily on Middle Eastern fuel imports, most of it shipped via the Strait of Hormuz during peacetime.