North Korea on Sunday attacked the South Korean foreign minister's recent international speech calling on the United Nations to severely penalize North Korea over its use of VX nerve agent.

North Korea's propaganda website Uriminzokkiri called Foreign Minister Yun Byung-se's speech in Geneva last week "psychotic slander" in its posting earlier in the day.

In the Conference of Disarmament in Geneva last week, Yun said North Korea's chemical weapons threats became a reality following the country's use of the VX nerve agent in the assassination of North Korean leader Kim Jong-un's half brother Kim Jong-nam in Malaysia on Feb. 13.

Yun also said North Korea should be stripped of its UN membership.

"It is a groundless slander and fabrication," the website said of Yun's remarks. "Those who are plotting biochemical warfare and posing biochemical weapons threats on us is none other than the US and the South Korean puppet regime," the website argued.

"(South Korea) may be forced to pay its price and Yun Byung-se and its conservative puppet group will see its fate doomed soon," it said.

North Korea is vehemently denying its role in the assassination of the leader's brother despite the Malaysian government's probe result showing that eight North Koreans were involved in the murder caused by the internationally banned nerve agent. (Yonhap)