AKIPRESS.COM - South Korea's military has fired warning shots at North Korean guards searching for a soldier who defected early morning, BBC reported.

The North Korean soldier had walked across the Demilitarized Zone (DMZ) shortly after 08:00 (23:00 Wednesday).

He had emerged from thick fog at a checkpoint, said the South's military.

He is the fourth North Korean soldier to defect this year. The incident comes weeks after one of the most dramatic defections in recent times.

In that incident, on 13 November, a soldier was shot as he fled across to the southern side of the Joint Security Area (JSA) in the village of Panmunjom. 

On Thursday, South Korea's defence ministry said its soldiers had fired around 20 warning shots when border guards from the North approached the border, appearing to be searching for the North Korean soldier who had defected hours earlier.

Yonhap news agency reported that the sound of gunshots coming from the North was heard 40 minutes later, although no bullets were found to have crossed the border.

The defection occurred along the border in Gangwon province, according to South Korea's national broadcaster KBS.

The soldier was taken into custody and Seoul said it was investigating what drove him to cross.

Very few North Korean defectors risk crossing to the South via the DMZ.

One of the world's most heavily guarded strips of land, the DMZ is a thin buffer zone between the two Koreas and is fortified on both sides with barbed wire, surveillance cameras, electric fencing and landmines.