n this photo provided by North Korea’s official Korean Central News Agency, Kim Yo-jong (circled in red), the sister of North Korean leader Kim Jong-un, watches as Kim Jong-un (front, in a black jacket) visits a construction site in North Pyeongan Province on Oct. 6. (Yonhap)

Kim Yo-jong, the powerful sister of North Korean leader Kim Jong-un, on Saturday condemned the United Nations for criticizing the country's recent test-firing of an intercontinental ballistic missile (ICBM), reaffirming Pyongyang's stance to retain nuclear weapons development.

U.N. Secretary-General Antonio Guterres on Thursday denounced North Korea's launch of a Hwasong-19 ICBM as a violation of U.N. Security Council resolutions.

Kim Yo-jong, vice department director of the Workers' Party's Central Committee, expressed "strong dissatisfaction" with Guterres' remarks, calling them "unfair and prejudiced" in a statement carried by the North's Korean Central News Agency (KCNA) on Saturday.

Kim accused countries "hostile" to North Korea of forming a military bloc based on nuclear weapons, asking, "Does the U.N. secretary-general think ... peace can be ensured on the Korean peninsula" if North Korea restrains itself?

She also reaffirmed the North Korean leader's stand of never changing the country's "line of bolstering" its nuclear forces.

"Have sanction, pressure and threats stopped us? They have only made us stronger," she said, stressing that the country "will never tolerate any attempt to threaten the security environment of the state."

In a separate statement carried by the KCNA, the North's foreign ministry also protested the UNSC's plan to convene on Monday on North Korea's latest ICBM launch.

The ministry accused "hostile forces" of creating a critical situation against the security environment of North Korea through "illegal double standards," strongly denouncing the meeting as a violation of the U.N. Charter and a "grave challenge" to international peace and security.

"The more provocative act the hostile forces take in defiance of the DPRK's grave warning, the stronger counteraction they will face," the ministry said, using the acronym for the Democratic People's Republic of Korea.