A North Korean soldier is expected to survive critical wounds after his old comrades fired a hail of bullets at him as he made a defection dash to South Korea, the South's government and military said on Tuesday.

On Monday, the soldier sped toward the border in a "peace village" in the heavily guarded demilitarised zone, in a four-wheel-drive vehicle.

But when a wheel came loose, he fled on foot as four North Korean soldiers fired about 40 rounds at him, said Suh Wook, chief director of operations at South Korea's Joint Chiefs of Staff, briefing lawmakers.

"Until this morning, we heard he had no consciousness and was unable to breathe on his own but his life can be saved," Suh said.

South Korea Australia

A North Korean soldier looks at the South through field glasses as a South Korean soldier, right, stands guard in the border village of Panmunjom in Paju, South Korea, on Oct. 12. (Ahn Young-joon/Associated Press)

Surgeons had removed five bullets from the soldier's body, leaving two inside, Suh added, to murmurs from lawmakers who said the soldier's escape was "right out of a movie."

The soldier took cover behind a South Korean structure in a Joint Security Area (JSA) inside the demilitarised zone between the two Koreas.

South Korean and U.S. soldiers, fearing more North Korean fire, later crawled to him to rescue him, the United Nations 
Command said in a separate statement.

North Korea has not said anything about the soldier. Its military had not given any indication of unusual movements on Tuesday, the South's military said.

1,000 defections per year

While on average more than 1,000 North Koreans defect to the South every year, most travel via China and it is unusual for a North Korean to cross the land border dividing the two Koreas, which have been in a technical state of war since their 1950-53 conflict ended in a truce, not a peace treaty.

The UN Command, in place since the end of the war, said an investigation into the incident was being conducted.

South Korean Defence Minister Song Young-moo said it was the first time North Korean soldiers had fired towards the South's side of the JSA, prompting complaints from some lawmakers that the South's military should have returned fire.

Moon Sang-gyun, the South's Defence Ministry spokesperson, said military operations at the JSA were usually conducted under the orders of the UN Command, which is in turn under orders from the U.S. military.

Severe intestinal injuries

The soldier, who was not armed, was flown in a UN Command helicopter to an operating theatre where doctors began working to save him even before he was out of a uniform that indicated he held a lower rank, Suh said.

South Korean officials have yet to identify where the soldier came from or what his intentions were.

Dr. Lee Cook-jong, the surgeon in charge of the soldier's care at the Ajou University Hospital, told reporters he was suffering from critical intestinal damage.

Hospital officials were under strict security agency orders not to talk to media and all updates on the soldier had to be through the military, workers there said.

Dr. Lee had been "given a talking-to" after a brief exchange with the media, the hospital workers said.

Unusual site for defection

The UN military armistice commission said it had informed the North Korean military that the soldier, who was found about 50 metres south of a Military Demarcation Line, was undergoing surgery.

Suh said the South had also informed the North on Monday of the soldier and his treatment, via loudspeakers on the border.

North Korea has in the past complained that North Korean defectors had been abducted by South Korea, and it has demanded their release.

This month, the North demanded that South Korea return 12 waitresses it said had been kidnapped while working in China in 2016. South Korea said the 12 women, and one man, had chosen to defect to the South.

Monday was the first time since 2007 a North Korean soldier had defected across the JSA.