A senior North Korean security official defected to South Korea earlier this year, a Seoul daily reported Thursday.

The State Security Department official, whose rank is equal to that of a Cabinet minister, entered South Korea while traveling abroad on a temporary duty, a source well versed in North Korean affairs told the Dong-A Ilbo newspaper.

The State Security Department is known to have played a key role in the 2013 execution of Jang Song Taek, North Korean leader Kim Jong Un's erstwhile mentor and uncle by marriage.

South Korea's state intelligence agency reported to parliament earlier this week that 46 high-ranking North Korean officials, who were mostly based in overseas offices, have fled to the South over the past three years.

Since taking power upon the death of his father in December 2011, Kim Jong Un has orchestrated a series of purges in apparent efforts to bolster his grip on power, resulting in a series of defections by officials.