The foreign ministry said that, at around 8:40 pm in Seoul (1140 GMT), "an explosion and fire occurred on a vessel operated by a South Korean shipping company... anchored in waters near the United Arab Emirates inside the Strait of Hormuz".

There had been "no casualties to date" among the 24 crew members on board, who include six South Koreans and 18 foreign nationals, the ministry said in a statement.

"The cause of the explosion and fire, as well as the specific extent of the damage, are currently being investigated," it said.

The vessel involved, the HMM Namu, is a cargo ship of almost 180 metres (590 feet) sailing under the flag of Panama, data from tracking site MarineTraffic showed.

Seoul's announcement came after Iranian state media said on Monday that Tehran's navy had fired "warning shots" in the strait, following the entry of American cruisers into the Gulf under a plan to help trapped commercial vessels leave.

Like many Asian economies, South Korea is highly dependent on fuel imports from the Middle East, much of which transit through the Strait of Hormuz.

Seoul has sought new sources of oil since the war caused the virtual shutdown of the waterway, although it also said last month that a South Korean tanker had made it through safely.

"The Korean government will communicate closely with relevant countries regarding this matter and take necessary measures to ensure the safety of Korean vessels and crew members within the Strait of Hormuz," the foreign ministry said on Monday.