North Korea soldier defects
A North Korean soldier has defected to South Korea as new defence chief appears in Pyongyang Jacky Chen/Reuters file photo

A North Korean soldier has defected to neighbouring South Korea through a heavily-fortified military border as a suspected new defence chief emerges in Pyongyang.

Braving the Demilitarised Zone, the most heavily militarised border in the world, the soldier, thought to be a teenager, turned himself in to South Korean forces.

"A North Korean man presumed to be a serviceperson defected to our side at around 08:00 am today [15 June]. He crossed the border in Hwacheon, Gangwon Province, on foot, and arrived at one of our guard posts. He then expressed his will to defect," a South Korean official told Seoul's Yonhap news agency.

No strange movements have so far been detected in the volatile border region over the past few days. There are no further details available about the defection as yet.

"It did not trigger an exchange of fire between the two sides. We are currently debriefing him to find out such details as his rank and motive for defection," the Seoul spokesperson said.

The defection comes as North Korean forces are believed to be planting anti-personnel mines along the inter-Korean border to prevent their soldiers from fleeing.

The Korean Central News Agency (KCNA) has published a photograph of Pak Yong-sik in close proximity with the leader Kim Jong-un, ramping up speculation that he may have been promoted as the new defence chief.

The four-star army general was seated next to Kim during the military event and North Korean watchers suspect he could have replaced the purged Hyon Yong-chol.

When asked about the development, South Korean unification ministry spokesperson Lim Byeong-cheol told reporters: "It is hard to verify it as the North has not officially named Pak as the arms force minister. But we are aware of media reports that there is a high probability over his appointment."