Four bodies have been found inside what appears to be a North Korean ship discovered in waters off Ulleung Island in the East Sea.

South Korea's Coast Guard said that a resident spotted and reported the wooden boat floating off the coast of the island at 9:50 a.m. Sunday. 

The nine-meter long wooden ship reportedly contained four skeletonized bodies. 

The coast guard set up a joint probe team with related authorities to investigate the ship and to identify the victims.

An increasing number of North Korean boats have drifted into Japan recently, sometimes with dead bodies in them, as more fishermen go further out to fish in deep waters.