A North Korean soldier shot multiple times while fleeing to the South in a rare and dramatic defection has had a second round of surgery but remains in a serious condition, his doctor said Wednesday.

The soldier suffered at least six gunshot wounds Monday as he dashed across the border at the Panmunjom truce village amid relentless firing by North Korean guards.

Lee Cook-Jong, a doctor treating the soldier, told reporters he was suffering a "prolonged state of shock from heavy bleeding" and although the surgery had gone well, he would likely have to undergo further operations.

He is currently on life support, Lee added.

The soldier was found collapsed and bleeding in a pile of fallen leaves on the South Korean side of the border and was airlifted to a hospital for emergency treatment.

It is very rare for the North's troops to defect at Panmunjom, a major tourist attraction and the only part of the border where forces from the two sides come face-to-face.

Unlike the rest of the frontier, the village is not fortified with minefields and barbed wire, with the demarcation line marked only by a low concrete divider.

Dozens of North Korean soldiers have fled to the South through the DMZ over the decades since the peninsula was divided, including two soldiers who crossed the frontier in June.

More than 30,000 North Korean civilians have also fled their homeland since the two nations came into being in 1948, but it is rare for them to cross the closely guarded border.