Seoul - North Korea on Friday warned of "merciless" action to stop the alleged abduction of its citizens by South Korean spy agents and activists.
The North's Committee for the Peaceful Reunification of Korea mentioned South Korea's spy agency chief Nam Jae-Joon by name as its "prime" target.
The abduction involving South Korean government institutions and "human scum" is a "wanton violation of sovereignty of other countries and international law", the state body said in a statement.
"The puppet regime's terrorism and conspiratorial plots are, in fact, hideous provocation against the people and social system of the DPRK [North Korea] and declaration of a war against it," it said.
The committee accused the South of using North Korean defectors for an espionage mission, or to slander Pyongyang, the committee said.
Those involved in abductions, smear campaigns against Pyongyang, and violators of its sovereignty "will be on the list of merciless punishment", it said.
The statement, carried by the North's official news agency, accused South Korea's spy agency of conspiring with Christian and other activists to kidnap North Koreans.
The North insists many of its citizens have been lured away from their homeland by South Korean government-sponsored human traffickers posing as religious activists.
The warning came a day after the North said a South Korean spy was captured recently while trying to use "dishonest elements" for a mission to destabilise its social system.
The North said the spy had been engaged in "plot-breeding activities" in a third country bordering the North while disguising himself as a religionist.
The South's National Intelligence Service (NIS) rejected the North's claim as "absurd and totally groundless".