A North Korean soldier defected to South Korea by crossing the heavily fortified Demilitarized Zone between the two countries on Sunday, the South's military said in a statement.

The soldier was taken into custody by South Korean guards who had been monitoring his movements, the military said, saying he would face an investigation over his defection.

Defections by North Koreans across the border are considered risky and most escapees make their way to the South through China or other third countries.

This is the first time a North Korean soldier has defected to the South since August last year.