North Korea leader Kim Jong-un looks to be tightening his grip on political power after reportedly punishing two key military figures for “impure behaviour”.

South Korean lawmaker Kim Byung-kee said Tuesday night that the country’s National Intelligence Service (NIS) told a closed door briefing that the two deposed officials were Vice Marshall Hwang Pyong-so and his deputy Kim Won-hong

Mr Hwang was head of North Korea’s General Political Bureau (GPB), also referred to as the General Political Department (GPD), which is being audited for the first time in 20 years.

The department is responsible for enforcing the political life of North Korea’s 1.1 million-strong military, including the state ideology of Juche and the life and teachings of the Kim family.

While it is unclear how the two high ranking officers were punished,  Andrei Lankov, a professor at Kookmin University in Seoul, told CNN the pair likely faced re-education including a period of re-indoctrination in North Korean ideology.

“He’s playing musical chairs with key positions,” Mr Lankov was quoted as saying.

“Kim Jong-un doesn’t want anybody in the military to stay in charge for too long … He’s brilliant, cynical, brutal and efficient.”

Before his punishment, Mr Hwang was one of three officials below Kim  in charge of the armed forces. 

Mr Hwang (L) was said to be one of Kim’s top-three military officials. Photo: AP

The high-level purge comes as a defector, shot as he crossed the Demilitarised Zone between North and South Korea, regained consciousness.

The soldier fled his post on the North Korean side of the border and was shot five times as he dashed toward Freedom House on the South Korean side.

The yet-unnamed soldier asked to watch television and is being shown South Korean films, South Korean news agency Yonhap reported.

“We believe the most life-threatening moment has now passed,” a government official was quoted as saying by the agency.

The soldier was shot at more than 40 times before reaching safety, the South says.

Medical staff say that he is traumatised from his ordeal.

“To provide psychological stability a South Korean flag has been placed hanging on the hospital room wall,” the government official told Yonhap.

Mr Hwang’s department was in charge of making sure soldiers like the defector are properly indoctrinated and never contemplate fleeing. The  soldier is the third to have defected from North Korea’s military this year.

Since taking office in late 2011, Kim has orchestrated a series of high-profile purges, dismissals and executions in what foreign experts say is an attempt to bolster his grip on power and remove anyone seen as a challenge to his leadership.

Mr Lankov said that since Kim took power in 2011, top military leaders are only averaging about one year in their jobs.

“If you look at generals, they are purged and replaced with unprecedented frequency,” he said.

“Once you get some kind of power support base, you are out. If you’re lucky, you are given some job as far away from the military as possible. If you are not lucky, you are just dead.”

Pyongyang is facing increasing pressure over its nuclear weapons program as the US Trump administration readies new sanctions a day after declaring North Korea a state sponsor of terrorism.

North Korea joined Iran, Sudan and Syria on the US terror blacklist.

– With agencies