The official Korean Central News Agency (KCNA) reported early on Friday that Kim Jong Un's uncle, Jang Song Thaek, had been executed on Thursday shortly after a special military trial. He was once considered the country's second-most powerful official behind his nephew Kim.

Calling Jang "worse than a dog", the North accused him of attempting to stand in the way of Kim's succession, according to KCNA.

On Monday, Pyongyang had confirmed that Jang had been dismissed from office after reports from South Korea's intelligence agency that he had been ousted late in November.

KCNA reported that "Jang and his followers committed criminal acts baffling imagination and they did tremendous harm to our party and revolution." Jang was accused of corruption, womanizing, drug-use and generally leading a "dissolute and depraved life."

Jang, who was married to the daughter of North Korea's founding leader Kim Il Sung, was seen as helping Kim Jong Un consolidate power following the December 2011 death of his father, Kim Jong Il.

The execution marks the most significant political upheaval in North Korea's top leadership since Kim Jong Un took power.

hc/msh (Reuters, AFP, dpa)