North Korea said on Friday (December 14) the uncle of leader Kim Jong Un, previously considered the second most powerful man in the secretive state, has been executed for treason, the biggest upheaval since the death of Kim's father two years ago.

The North's official KCNA news agency said Jang Song Thaek had been executed after a special military tribunal found him guilty of treason, only days after he was stripped of all posts and expelled from the ruling Workers' Party.

News of the execution followed a swirl of unconfirmed media reports that one or more of Jang's aides had defected to South Korea. The South's spy agency says it has no knowledge of any such defections.

If true, the execution caps a spectacular downfall for a man who had long been a fixture in North Korea's leadership.

"The accused Jang brought together undesirable forces and formed a faction as the boss of a modern day factional group for a long time and thus committed such hideous crime as attempting to overthrow the state," KCNA said.

The official Rodong Sinmun newspaper also on Friday carried a photograph of Jang in handcuffs and being held by uniformed guards as he stood trial. It is not known how the sentence was carried out.

Jang was a vice chairman of the powerful National Defence Commission and a member of Workers' Party politburo.

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