In what could be the most significant political event to affect North Korea since the death of Kim Jong-Il and rise of his son Kim Jong-un, the country's second most powerful official has been 'purged' from his powerful position.

An address on state TV said General Jang Song Thaek was guilty of "dissolute and depraved" behaviour and of "dreaming different dreams".

The sacking of Jang comes after reports in South Korean media that one of his aides had sought asylum in South Korea.

The North's official KCNA news agency said General Jang had been removed from all his posts and sacked from the ruling Workers' Party during a meeting of its politburo. It's reported the meeting was attended and "guided" by the country's leader, who is also Jang's nephew.

"Jang and his followers committed criminal acts baffling imagination and they did tremendous harm to our party and revolution," the report explained. "Jang pretended to uphold the party and leader, but was engrossed in such factional acts as dreaming different dreams and involving himself in double-dealing behind the scenes."

The report also states, "Affected by the capitalist way of living, Jang committed irregularities and corruption, and led a dissolute and depraved life."

The report did not say if Jang had been detained or charged with any crime. It also failed to mention the unidentified defected aide, who managed funds for him.

According to cable news network YTN and the Kyunghyang Shinmun newspaper, the aide was being protected by South Korean officials in a secret location in China.

If his defection is confirmed, it would be the most serious for North Korea in 15 years.

South Korea's National Intelligence Service previously said it believed General Jang had been relieved of his posts in November. It also said two of his close associates had been executed recently for corruption.

Among Gen Jang's senior party and military posts, he was vice chairman of the country's top military body, the National Defence Commission.

Gen Jang is married to Mr Kim's aunt, the daughter of the North's founding leader Kim Il-Sung, and was widely considered to be working to ensure his nephew firmly established his grip on power in the past two years.

A South Korean official said last week that Gen Jang was probably alive and in no immediate physical danger, as was his wife, Kim Kyong Hui.

Experts familiar with the political situation in the secretive state say Jang's removal will help Mr. Kim consolidate his power base with a group of younger aides.