SEOUL, May 4 (Xinhua) -- An explosion and fire occurred Monday on a South Korean-operated vessel anchored inside the Strait of Hormuz, South Korea's foreign ministry said.

The vessel, HMM NAMU, flying the Panamanian flag, has six South Korean crew members and 18 foreign crew members aboard, with no casualties reported so far, the ministry said.

The cause of the explosion and fire, as well as the exact extent of the damage, was still being investigated, it added.