The UN Security Council is discussing North Korea's human rights record, despite opposition from China and Russia.
It comes days after the UN General Assembly voted in favour of referring North Korea to the International Criminal Court to face charges of crimes against humanity.
North Korea has meanwhile reportedly suffered a large-scale internet outage.
Last week, the US said North Korea was behind a cyber attack on Sony Pictures.
It is the first time the UN Security Council has discussed the country's human rights record.
US envoy Samantha Power described North Korea as "a living nightmare", and said a UN report showed the country's brutality.
The report by a UN human rights inquiry in February said that ordinary North Koreans faced "unspeakable atrocities", including "deliberate starvation, forced labour, executions, torture" and political repression.
North Korea refused to co-operate with the report and condemned its findings. It is not attending the Security Council meeting.
Speaking on Monday, North Korean envoy Kim Song told AFP: "We cannot recognise the Security Council meeting. Its mandate is not human rights."
China and Russia also attempted to block the subject from being discussed at the Security Council. However, they were overruled by other members.
Internet 'totally down'
Meanwhile, a US-based Internet performance firm said that North Korea was experiencing severe internet outages.
Connectivity had worsened over the weekend and was now "totally down", Doug Madory, director at Dyn Research, said.
It was not clear what had caused the outages, Mr Madory said, adding that a software glitch, or a cyber attack, were possibilities.
The US government has declined to comment on the internet outage.
"We aren't going to discuss ... publicly, operational details about the possible response options or comment on those kind of reports in any way except to say that as we implement our responses, some will be seen, some may not be seen," state department spokeswoman Marie Harf said.
Last week, the US government said an FBI investigation had shown that North Korea was behind a hacking attack on Sony, which led to unreleased films and private emails being leaked online.
US President Barack Obama vowed a response to the attack.
North Korea dismissed the US accusations and denied being responsible, although it also praised the Sony attack.
The eventual fallout from the attack saw Sony cancel the Christmas release of a comedy called The Interview, a film depicting the assassination of the North Korean leader.