A crewless Chinese-flagged cargo vessel sank in waters off the southwestern Jeolla county of Sinan Wednesday morning, prompting the Coast Guard to investigate the possibility of illegal entry by its passengers.

According to the Coast Guard, a local fishing boat reported the 200-ton ship sinking some ten meters west of Gageo Island at around 7:30 a.m., and authorities responding to the call found no personnel onboard the vessel or in the surrounding waters.

A search operation involving the Coast Guard, the Navy, and the police in waters near Gageo Island, Heuksan Island, and the South Jeolla regions of Jindo and Mokpo has been launched on suspicion that the passengers may have snuck into the country.

The Coast Guard is also expected to take steps to prevent a possible oil leak after the vessel sank completely at around 10 a.m.