Lim also said the killing of Kim Jong-nam is clearly a terrorist act, noting he was killed by nerve agent VX, a banned chemical weapon.

The comments are widely seen as South Korea's attempt to put pressure on North Korea after North Korea and Malaysia resolved their diplomatic standoff over Kim's killing.

Kim was killed at Kuala Lumpur International Airport on Feb. 13 after two Asian women rubbed what the Malay police later said was nerve agent VX on Kim's face.

Eight North Koreans were named as suspects in the case, though North Korea has denied any involvement and claimed that Malaysia colluded with South Korea over its probe into the case.

Nine Malaysians returned home late March after the North allowed their departure from Pyongyang in exchange for Malaysia's agreement to hand over Kim's body to the North and allow three North Korean suspects in the case to leave the Southeast Asian country.

North Korea is a member of the ASEAN Regional Forum, Asia's biggest security gathering. The Association of Southeast Asian Nations is comprised of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam. (Yonhap)