North Korea has confirmed that Chang Song-thaek, the once powerful uncle of leader Kim Jong-un, has been dismissed, accusing him of criminal activity.

He was denounced by the state-run news agency for corruption and "depraved" acts such as womanizing and drug abuse.

Seen as an economic reformer, Mr. Chang regularly handled talks with China, Pyongyang's only major ally.

Images released by North Korea showed Mr. Chang being removed from a Politburo meeting by uniformed guards.

The source said the decision came after a meeting of the ruling communist Korean Workers' Party Politburo.

News of his dismissal filtered out in South Korea last week along with reports that two of his close aides had been executed for corruption.

Analysts say it is the biggest upheaval in North Korea's leadership since Mr. Kim succeeded his father two years ago.