A North Korean soldier defected to South Korea through the inter-Korean border Monday, an official from the Ministry of National Defense said.

"A North Korean man presumed to be a serviceperson defected to our side earlier this morning," a ministry official said, requesting anonymity.

"He crossed the border in Hwacheon, Gangwon Province, on foot, and expressed his will to defect," he added, noting that he has been under investigation by relevant authorities.

Other details including the identity of the man and his motive are yet to be known.

Over the past several years, South Korea has seen a series of defection cases from the poverty-stricken communist neighbor. But it is not usual for North Korean soldiers to walk crossing the Military Demarcation Line to defect.

According to military sources here, the communist country has been striving in recent weeks to prevent defection through the demilitarized zone by beefing up patrols along the inter-Korean border and checking to see if border markers are properly set up. A total of 1,292 markers made out of either wood or concrete are established every 200 to 300 meters along the tensely-guarded border.

North Koreans, many of whom are civilians, usually cross the relatively porous border with China first and then try to head to South Korea, often through Southeast Asian nations. In 2014 alone, a total of 1,396 North Koreans defected here, according to government data. (Yonhap)