Kim made his comment in his New Year address.
Jang Song Thaek, the 67-year-old uncle and mentor of the unpredictable North Korean leader who had been the country's second-most powerful man, was suddenly purged last month on various charges after being stripped of all his powerful posts. Jang's execution, which shocked the world, was seen as part of Kim's effort to consolidate his leadership in the isolated Communist country since taking the helm upon the death of his father Kim Jong Il in December 2011.
"In the seething period of the effort for building a thriving country last year, we took the resolute measure of removing the factionalists lurking in the party [Workers' Party of Korea]," CNN reported Kim said in his address carried by the state media.
"As our party detected and purged the anti-party, counter-revolutionary factionalists at an opportune time and with a correct decision, the party and revolutionary ranks were further consolidated and our single-hearted unity was solidified to the maximum."
Jang had been accused of various charges, including trying to overthrow the nuclear-armed government. He had been married to Kim Jong Il's sister.