Kim Jong-Un's half-brother was killed at a Malaysian airport on 13 February
Former officials working for two North Korea ministries are wanted for questioning over the murder of leader Kim Jong-Un's half-brother.
Kim Jong-Nam, 45, was killed at a Malaysian airport on 13 February by assassins using VX nerve agent, a chemical that can kill in minutes and is listed by the UN as a weapon of mass destruction.
Lee Cheol-Woo, an official briefed by South Korean intelligence, said: "Among eight suspects in this case four are from the ministry of state security and two who actually took action are from the foreign ministry.
"That is why it is a case of terrorism led by the state, directly organised by the ministry of state security and the foreign ministry."
Malaysian police have identified eight North Koreans as suspects or as wanted for questioning, including a North Korean embassy official believed to still be in Kuala Lumpur.
Malaysian health minister Subramaniam Sathasivam said on Sunday that Kim Jong-Nam died within 15-20 minutes of being assaulted by two women who are believed to have smeared VX on his face.
The women, Indonesian Siti Aisyah, 25, and Vietnamese Doan Thi Huang, 28, are in police custody and have told officials they believed they were taking part in a TV prank.
Another South Korean official briefed by the intelligence agency, Kim Byung-Kee, said the North Koreans had operated in three teams.
Two teams are said to have been responsible for hiring women in Indonesia and Vietnam and bringing them to Malaysia to carry out the attack and another was a "back-up" team.
The killing has sparked a diplomatic stand-off.
Malaysia has refused to hand over the body to North Korea before it is officially identified by the victim's next of kin.
Meanwhile, North Korea has reportedly executed five senior security officials for making false reports to Kim Jong-Un.
South Korea's intelligence agency said they were killed using anti-aircraft guns.