North Korean leader Kim Jong-il has apointed his brother-in-law as the North's chief internal security supervisor.

South Korean Sources on North Korea said Jang Song-thaek's promotion to the director of the Administrative Department of the ruling Workers' Party in early October reflected his return to the center of power.

The sources say the post re-established last month by the North Korean leader oversees the communist state's internal security organs, including the prosecution, police and the judiciary.

The 61-year-old technocrat married Kim Jong-il's younger sister, Kyong-hui, in 1972. Jang was thought to be the North's Number Two man before he was purged in 2004 for being power hungry and taking part in separatist activities.