The U.S. ambassador to the U.N., Samantha Power, tried to quiet the diplomats at the event that featured more than 20 defectors. She called North Korea's statements “totally self-discrediting.”

The North Korean diplomats did not comment as they left the chamber after diplomat Ri Song-chol read out a statement in protest of the event, even as North Korean defectors stood and shouted in their faces.

Nuclear-armed North Korea has been on the defensive ever since a groundbreaking U.N. commission of inquiry detailed vast rights abuses there. North Korea has repeatedly referred to defectors who cooperated in the inquiry “human scum.”

Defectors stood up and shouted in Korean as Power and others called for calm and a U.N. security team assembled. An observer who speaks Korean said the shouts included “Shut up!” “Free North Korea!'' “Down with Kim Jong-un!'' and “Even animals know to wait their turn.”

“There is no need for a microphone,” Power said as one North Korean diplomat persisted in reading out a statement that referred to “ungrounded allegations” and “hostile policy” toward his country. A microphone was briefly turned on for the diplomats.

Power continued: “Please shut the mike down because this is not an authorized presentation. ... Please ensure that the microphone is not live. ... We are calling U.N. security.”

As soon as the North Korean diplomat stopped talking and the next featured defector, Jay Jo, started speaking, the North Korean diplomats stood and walked out.

“They're so rude,” Jo said later, adding that she wished that the diplomats had stayed so she could have spoken with them. The U.S. said North Korea had been informed before the event that it would have a chance to speak.

The brief chaos came minutes after U.N. Assistant Secretary-General for Human Rights Ivan Simonovic told the audience that North Korea had shown “new signs of engagement” on human rights issues in recent months.