Dozens of parasites, some as long as 27 centimetres, have been found in the ruptured intestines of a North Korean soldier who fled to the south, surgeons say.

Key points: While soldier's vital signs are stabilising, he continues to remain unconscious

While soldier's vital signs are stabilising, he continues to remain unconscious "I have not found parasites this big in the intestines of South Koreans," a medical expert says

"I have not found parasites this big in the intestines of South Koreans," a medical expert says The soldier defected to the South on Monday

The defector was severely wounded by gunfire while escaping to South Korea and has had two surgeries, hospital officials say, but it was too early to tell whether he would make a recovery.

While the soldier's vital signs are stabilising, he remains unconscious and is relying on a breathing machine.

While treating the wounds, surgeons removed dozens of parasites from the soldier's ruptured small intestine, including presumed roundworms that were as long as 27 centimetres, which may be reflective of poor nutrition and health in North Korea's military.

"I spent more than 20 years of experience as a surgeon, but I have not found parasites this big in the intestines of South Koreans," Lee Cook-jong, who leads the soldier's medical team, told reporters.

Doctors measured the soldier as being 170 cm tall, but weighing just 60 kilograms.

Not clear if the North violated armistice agreement

The unarmed soldier, whose name and rank have not been disclosed, defected to the South on Monday by driving a military jeep near a line that divides the Koreas at the Joint Security Area (JSA), and then rushing across it under a barrage of bullets.

Map showing how North Korean soldier defected to South Korea. ( Reuters )

South Korea's military said four North Korean soldiers used handguns and AK rifles to fire about 40 rounds at their former comrade, who was hit at least five times.

He was found beneath a pile of leaves on the southern side of the Joint Security Area, and South Korean troops crawled there to recover him.

A United Nations Command helicopter later transported him to the Ajou hospital.

It remains unclear whether the North Koreans chasing the soldier fired at him even after he crossed into the southern side of the border, which would be a violation of an armistice agreement that ended the 1950-53 Korean War.

The United Nations Command, which is investigating the incident, postponed a plan to release video footage of the soldier's escape on Thursday.

The JSA is jointly overseen by the American-led UN Command and by North Korea, with South Korean and North Korean border guards facing each other only meters apart.

It is located inside the 4-kilometre-wide Demilitarised Zone, which forms the de facto border between the Koreas since the Korean War.

The 4-kilometre-wide Demilitarised Zone forms the de facto border between the Koreas since the Korean War. ( ABC News: Susan Kim )

AP