SEOUL (AFP) - North Korea confirmed on Monday that the powerful uncle of young leader Kim Jong Un has been purged, with state TV airing humiliating images of Jang Song Thaek being dragged away by uniformed officers.

The official news agency KCNA accused the man once seen as the power behind the throne of being a corrupt, drug-taking womaniser bent on building his own faction in the ruling party.

South Korean analysts predicted a sweeping purge would follow, leaving Kim as the undisputed centre of power.

KCNA said Jang, once seen as his nephew's mentor, had been stripped of all his posts and of party membership for committing criminal acts and leading a "counter-revolutionary faction".

It said the decision was taken on Sunday at a high-level meeting of the ruling Workers' Party attended by Kim.

State TV on Monday showed photos of Jang being dragged out of his seat at a meeting by two officers - an extremely rare publication of humiliating images involving a senior official.

It was not certain if the incident happened at Sunday's meeting. But the TV aired other photos from Sunday showing a stony-faced Kim sitting at the podium with other top officials.

Analysts said Jang's main role had been to ensure a smooth transition after the inexperienced Kim Jong Un came to power following the death of his father Kim Jong Il in December 2011.

But they said Jang had become increasingly resented by the leader, who is aged about 30.

"Jong Un has built a solid power base for the past two years, and he no longer needed a regent who appeared to be increasingly powerful and threatening," said Paik Hak Soon, a researcher at the South's Sejong Institute think tank.

South Korea's spy agency said last week that Jang had apparently been purged and two associates executed, in the secretive nation's biggest political upheaval since the death of Kim Jong Il.

Free North Korea Radio - a Seoul-based radio station run by North Korean defectors - claimed Jang had already been executed on Thursday and that the latest photos of him had been taken well before Sunday's meeting.

Citing high-level sources in the North, it claimed Jang and six other party and military cadres who were close to him had been executed in the capital Pyongyang.

Seoul's spy agency and the unification ministry that handles cross-border affairs said they had no knowledge of the reported execution.