The disappearance of one of Kim Jong-un's top aides has sparked rumours that he may have been executed.

General Hwang Pyong-so, who was once at the heart of the North Korean leader's inner circle, has not been seen in public since 13 October.

The general was pictured standing next to Kim at a memorial service for his father Kim Jong-il last year and most recently in September when Pyongyang carried out its sixth nuclear test.

South Korea's spy agency told a parliamentary hearing last month that Hwang and his deputy, Kim Won-hong, had been punished for their "impure attitudes" towards the North Korean leader.

A source told South Korean newspaper JoongAng Ilbo this week that the pair had been receiving kickbacks in exchange for promotions in the army's Politburo.

Upon hearing about this, Kim reportedly told Choe Ryong-hae, vice-chairman of the Workers' Party, to "punish them as a warning to others." It is unclear how they were punished.

The newspaper suggested that Hwang could have followed in the footsteps of Jang Song-thaek, Kim's uncle and his most trusted general before his arrest in 2013. He was accused of being a counter-revolutionary and executed.

"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," JoongAng Ilbo reported.

Several other members of Kim's inner circle have been executed in recent years, including his deputy public security minister O Sang-hon who was reportedly killed by a flamethrower.

In 2014, Kim Chol, a vice minister in the army, was executed by a mortar bombardment for "drinking and carousing" during the official mourning period for Kim Jong-il, South Korean media reported.

Kim Jong-un  Hwang Pyong-so
General Hwang Pyong-so was once at the heart of Kim Jong-un's circle but has not been seen in public since early October. AFP/Getty Images