The terror group was acting on the instruction of intelligence agencies of the US and South Korea, according to Kim Hyun Joong.
"[North Korea] has exposed a criminal group planted by the CIA and the South Korean intelligence service to carry out state-backed terror [plot] by the means of biological and chemical weapons against our leadership," the ambassador said during a press conference in Moscow on Friday.
Organizers of the attempts to assassinate the leadership of North Korea will be 'mercilessly destroyed,' North Korean Ambassador said.
"The Ministry of State Security of North Korea has announced that it will find and mercilessly destroy the organizers behind the [planned] terror [attacks] from the CIA and National Intelligence Service of South Korea to the last one," the ambassador vowed.
US' hostile acts against North Korea have recently reached an extreme degree and go beyond all limits, the ambassador added.
"If South Korea <…> maintains its pro-US confrontational posture, they will be doomed," Kim Hyun Joong concluded.
Last week, North Korea accused the US and South Korean intelligence agencies of attempting to assassinate its leader Kim Jong-un.
US Department of Defense spokesperson Capt. Jeff Davis refuted the accusations, saying that there was "no reality that would match them."