The continued absence of the director of the most powerful North Korean military organisation has triggered concerns for his safety.

Hwang Pyong-so – who leads the North Korean army's political bureau and sits on the Workers' Party's Central Committee – has been expelled from the party for taking bribes, a South Korean source told Seoul-based newspaper JoongAng Ilbo.

The military boss' deputy, Kim Won-hong, has also been detained at a prison camp for the same crime, the paper reported.

"If Hwang was indeed kicked out of the Workers’ Party, it would practically mean the end of his political career, and possibly his life, though it is unknown whether or not he is still alive," the newspaper said.

Kim Jong-un decided to "punish them as a warning to others" because he suspected the pair were receiving payments in exchange for promotions, the source said.

The South's intelligence agency in November said the two men appeared to have been punished for holding "impure attitudes" towards the isolationist state's leader.

Vice chairman of the Workers' Party Choe Ryong-hae – reportedly a rising star in the North Korean regime – is alleged to have led the investigation into the army's political bureau.

Information on North Korea is difficult to obtain, and since there is little hard evidence of Mr Hwang's condition, analysts have been reluctant to draw firm conclusions about his safety.

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A number of high-profile North Korean officials are known to have been executed in recent years, including Hang Song-thaek, Mr Kim's uncle.