Doctors have said a North Korean soldier who defected to the South is riddled with parasites.

The soldier was shot five times while crossing the border at the heavily-guarded Demilitarised Zone (DMZ).

While he was dragged to safety by South Korean troops, the soldier is still said to be in a critical condition in hospital.

In comments to journalists quoted by the AFP news agency, doctor Lee Cook-Jong said: "Vital signs including his pulse are returning to stability. We're paying close attention to prevent possible complications".

However, officials also indicated that parasites had made treatment more difficult.

Dr Lee noted that "an enormous number of parasites" - including roundworms - had been found in the soldier's small intestine.

One of the worms removed is said to have been 27 cm long.

Experts have said that parasite infections through contaminated food are believed to be common in North Korea, where human faeces are still sometimes used to fertilise crops.