An elderly South Korean male tourist was missing after falling off a cruise ship off the country's east coast Saturday, the coast guard said.

The 75-year-old, identified only by his family name Jeong, fell overboard three kilometers northwest of Jumunjin, a port on the east coast, at around 2:50 p.m., it said.

Coast Guard officials said they sent ships and a helicopter to the area to search for the missing man.

The search was suspended due to darkness and will resume on Sunday, they said.

Lee Dong-ju, a coast guard official, said an investigation was under way to determine what caused the accident.

Meanwhile, the operator of the 753-ton ship, Risabu Cruise, said it suspects that the man who was traveling alone might have jumped overboard in a suicide attempt.

"Our personnel told the man to stay away from the ship's rail, but he was later found to have disappeared after our personnel had left the scene," Kim So-young, an official of Risabu Cruise, said by phone.

Company officials said they were checking surveillance cameras to find out more details.

Risabu Cruise said that the vessel was sailing to Gyeongpodae, a nearby beach, from Jumunjin when the accident occurred. (Yonhap news)