A high-ranking North Korean official was executed because he talked back to the Supreme Leader and fell asleep during an event attended by the dictator.

The latest execution in North Korea was held on April 30, the South Korean intelligence report said, according to Reuters, and was one of the most brutal because the late officer was blasted by an anti-aircraft gun at a firing range.

The newest victim of North Korea's high-level purge was 66-year-old Hyon Yong Chol, who acted as the National Defense Chief of North Korea and had been appointed by Kim Jong-un's late father Kim Jong-il, the publication said.

Three days after Hyon Yong Chol was arrested - with no trial - Hyong Yong Chol was charged with treason and disobedience, a related report by BBC said.

This follows the 15 other high-level executions directed by Kim Jong-un since he took over the leadership of North Korea in 2011. In 2013, he ordered the execution of his own uncle, Jang Song Thaek, whom he accused of inciting factionalism damaging to the economy.

Likened to the purges made by the former Russian dictator Josef Stalin, Kim Jong-un is showing those against him that he is ultimately in control, especially of the military.

Kookmin University's specialist on North Korean affairs, Andrei Lankov, told Reuters that this does not necessarily mean instability in the government. The flexing of political muscles is more a show of force on the part of Kim Jong-un to instigate fear in those that contradict him.

Lankov noted that the installation of fear has so far pacified the instability in Kim Jong-un's rule, which has been rocky for three years.

The public executions of high-ranking officers had not been officially acknowledged by North Korea, according to the Wall Street Journal.

South Korea's Unification Ministry spokesman Lim Byung-chul said the North Korean Defense Minister Hyon was last seen in public late last month, but his current whereabouts could not be confirmed.