Kim Jong Un executes Kim Yong Jin by firing squad for allegedly disrespecting the leader during North Korea's Supreme People's Assembly in June.
North Korea executed its vice premier for education in July for showing disrespect to leader Kim Jong Un during a meeting in Pyongyang, and banished two other officials to rural areas for re-education, South Korea said on Wednesday.
Since taking power after his father's death in late 2011, Kim Jong-Un is believed to have executed or demoted a number of senior figures in what analysts say is an attempt to tighten his grip on power.
"Vice premier for education Kim Yong Jin was executed," Seoul's Unification Ministry spokesman Jeong Joon-Hee said at a regular briefing.
Kim Yong Jin was killed by a firing squad in July as "an anti-party, anti-revolutionary agitator," added an official at the ministry, who declined to be named.
"Kim Yong Jin was denounced for his bad sitting posture when he was sitting below the rostrum" during a session of North Korea's parliament, and then underwent an interrogation that revealed his other crimes, the official told reporters.
JoongAng Ilbo, a south Korean newspaper, first reported on Tuesday top figures had been punished, but identified the education official by a different name.
"He incurred the wrath of Kim after he dozed off during a meeting presided over by Kim. He was arrested on site and intensively questioned by the state security ministry," it quoted a source as saying.
Fall of spymaster
The unification ministry said two other senior figures were forced to undergo re-education sessions.
One of them was Kim Yong Chol, a top official in charge of inter-Korean affairs and espionage activities against the South.
The 71-year-old Kim Yong Chol is a career military intelligence official who is believed to be the mastermind behind the North's frequent cyberattacks against Seoul.
Kim Yong Chol is also blamed by the South for the sinking of a South Korean warship in 2010 near the disputed sea border with the North in the Yellow Sea.
Kim Yong Chol was banished to an agricultural farm in July for a month for his "arrogance" and "abuse of power," the ministry official said.
Kim Yong Chol, who was subsequently reinstated this month, is likely to be tempted to prove his loyalty by committing provocative acts against the South, the official said.
"Therefore, we are keeping a close tab on the North", he said.
South Korea's Yonhap news agency put the number of party officials executed during Kim Jong Un's rule at over 100.
In April 2015, it was reported that defence minister Hyon Yong-Chol was summarily executed with an anti-aircraft gun.
Reports of the latest execution coincide with a series of high-profile defections from the North.
North Korea's deputy ambassador to Britain has defected to the South with his family, the unification ministry said earlier this month.
Thae Yong-Ho was driven by "disgust for the North Korean regime" and concerns for his family's future, it said.
At least 12 waitresses and their manager who had been working at a North Korea-themed restaurant in China also made headlines when they arrived in the South in April as the largest group defection in years.
About ten North Korean diplomats made it to the South in the first half of this year alone, Yonhap said, quoting informed sources.