North Korea on Friday threatened to take action against the head of South Korea's spy agency for masterminding the kidnapping of its citizens and for plotting to undermine the country's sovereignty.

The spokesman for the North's Committee for the Peaceful Reunification of Korea said Seoul is using the National Intelligence Service (NIS) to carry out anti-DPRK activities. The DPRK stands for the Democratic People's Republic of Korea, the North's official name.

He warned that all those who take part in such undertakings will be eliminated, and singled out Nam Jae-joon, the director general of the NIS, as being on the top of the list for the country's retribution.

The committee in charge of managing inter-Korean relations said measures to get rid of the "criminal" will be implemented immediately, and claimed such a move is sanctioned by both North Korean and international law.

"The DPRK's action comes as the NIS has used anti-North Korean groups such as Durihana, to kidnap its citizens and collect information with the aim of triggering internal revolt," the official said.

The spokesman added that besides Nam, anyone who tries to violate the basic rights of North Koreans will have no place to hide. He emphasized that his remarks are not empty threats.

Related to the latest verbal attacks, North Korea watchers in Seoul said that singling out Nam may be a sign that Pyongyang has come to the realization that it must not stand by and let the South implement policies that could lead to more defections by its people. 

Meanwhile, the North said on Thursday it caught a spy who tried to infiltrate its capital city to make contact with "dishonest people."

The NIS said such claims were preposterous and refuted allegations that the man the North is holding is an agent. (Yonhap News)