A DRUNK North Korean who turned up in a South Korean town in his underwear said he floated there hanging on to some driftwood.

South Korea's Yonhap News Agency reported that the military and police were questioning the man, believed to be in his 20s, after he was found on Sunday hiding in the town of Ganghwa, west of Seoul.

The man was found in his underwear, still drunk.

"The man said he crossed to the South, holding on to a floating object to waters off the coast of Gyodong Island," army spokesman Lee Bung-woo said.

"The floating object is seen as a wooden board that drifted due to the flood in the North."

Marine Corps were trying to pin down whether the man intended to cross the border, or did it by accident.

South Korean policy is to return North Koreans who accidentally drift south, but accept defectors who want to live there permanently.