South Korea's top envoy to the UN on Friday criticized as "bizarre" and "deplorable" North Korea's claim that its sending of trash-filled balloons to the South was an exercise of freedom of expression.

Ambassador Hwang Joon-kook made the remarks during a UN Security Council meeting as the North has sent waste-loaded balloons to the South in a tit-for-tat response to South Korean activists' sending of anti-Pyongyang leaflets across the inter-Korean border.

In a sarcastic statement last month, Kim Yo-jong, the influential sister of North Korean leader Kim Jong-un, claimed that the sending of the balloons to the South was a move based on North Korean people's freedom of expression.

"The DPRK's recent claim that Pyongyang's sending of trash balloons to South Korea was North Korean people's exercise of freedom of expression is an example of a bizarre and deplorable interpretation of freedom of expression," Hwang said during the meeting on international peace and security.

DPRK stands for the North's official name, the Democratic People's Republic of Korea.

He stressed that freedom is limited only by boundaries strictly defined by international law.

"It must not be misinterpreted and distorted," he said.

At the meeting, the ambassador reiterated Seoul's stance against "all forms of violence, discrimination and incitement to hatred."

"We cannot accept acts of violent extremism and hate speech that undermine the freedom of others, particularly the vulnerable," he said.

In recent weeks, tensions rose on the Korean Peninsula due to the North's sending of trash balloons, which caused disruptions to the life of people living near the inter-Korean border.

Matthew Miller, the spokesperson for the State Department, called the North's sending of balloons a "disgusting" and "childish" move.