North Korea on Thursday accused UN Secretary-General Antonio Guterres of being a "kind of henchman who is representing the United States" after the UN chief said sanctions were essential to pressure Pyongyang.
North Korea's mission to the United Nations released a statement complaining of "reckless remarks" by Guterres during the Munich Security Conference last week.
At the conference, Guterres praised the Security Council for succeeding in putting "through sanctions a very meaningful pressure over North Korea," adding: "The pressure in my opinion is absolutely essential to be maintained."
"This is nothing but an absurd sophistry inappropriate to his duty as secretary-general of the United Nations and only make us to think whether he is a kind of henchman who is representing the United States," said the North Korean mission in a statement.
North Korea argued that the United States was at fault for the crisis on the Korean peninsula and that Pyongyang's nuclear and missile tests were a legitimate form of self-defense.
Guterres' remarks were "ill-minded", said the mission, before requesting that the UN chief "refrain from his behavior acts like somnambulist any further."
Led by the United States, the Security Council last year imposed three new sets of sanctions on North Korea aimed at piling pressure on Pyongyang to abandon its nuclear and missile tests.
The economic measures are aimed at cutting off revenue to Pyongyang's military programs.
During a visit to South Korea this month, Guterres met briefly with North Korea's ceremonial head of state Kim Yong Nam and urged dialogue to address the crisis.
The UN chief has been a strong supporter of the thaw in relations between Pyongyang and Seoul during the Olympics, which he maintains could provide the basis for a broader dialogue.
In December, Guterres dispatched UN political chief Jeffrey Feltman to Pyongyang for talks, but the envoy came back with no commitment from North Korea to hold negotiations on the nuclear standoff.