Kim was assassinated at Kuala Lumpur International Airport in 2017 when two women smeared his face with what appeared to be a nerve gas.
Two women pleaded not guilty Monday to murdering the half-brother of North Korea's leader, at the start of their trial in Malaysia over the Cold War-style assassination that shocked the world.
Kim is the long-estranged half-brother of North Korea's ruler, and the North has refused to acknowledge he was the victim of the Feb. 13 murder.
North Korea and Malaysia Tuesday banned each other's citizens from leaving their countries, with Kuala Lumpur saying its nationals were effectively being held "hostage".
Kim Jong-Nam, 45, was poisoned on February 13 at Kuala Lumpur International Airport with VX, a nerve agent so deadly that it is classed as a weapon of mass destruction..
The spokesman maintained that Pyongyang opposed "all forms of terrorism" and accused the US of trying to tarnish its reputation.
Police also requested the second secretary at the North Korean embassy in Malaysia to assist the probe as a diplomatic rift between Kuala Lumpur and Pyongyang widens.
This proves Malaysia's intention to politicise the transfer of the body in utter disregard of international law and morality and thus attain a sinister purpose, North Korea jurists said.
CCTV footage aired on Japanese television on Monday gave the first public glimpse of the apparent moment Jong-Nam was attacked at Kuala Lumpur International Airport.
Malaysia on Monday summoned the North Korean ambassador over his accusation that it conspired with "hostile forces" as it investigates the murder of leader Kim Jong-Un's half-brother, officials said.
"Considering that the five suspects are North Korean nationals, we view that the North Korean government is behind the incident," an official from Seoul's unification ministry said.
Forensic specialists were on Friday carrying out tests on the body to try to determine the toxin that was apparently sprayed in his face as he readied to board a plane earlier this week.
Kim Jong-nam used social media site extensively, under the alias ‘Kim Chol’, and had photos of him in casinos and famous hotels in the city, sources said.
"We will facilitate the request by any foreign government although there are procedures to be followed," deputy PM Ahmad Zahid Hamidi said.
Kim Jong-Un has been trying to strengthen his grip on power in the face of growing international pressure over North Korea's nuclear and missile programmes.