The United Nations' top human rights official says some 200,000 people are being held in prison camps in North Korea where they are being subjected to torture, rape and slave labour.
In a rare statement on the country, Navi Pillay said North Korea has one of the worst but least understood and reported human rights situations in the world.
Ms Pillay says stronger action is needed against what amounts to crimes against humanity.
A spokesperson for Ms Pillay, Rupert Colville, says an international investigation is needed into the abuses.
"People are executed just because they say something, people are tortured, women are raped by the guards, babies are born with absolutely no medical help, no extra food, nothing. And the general conditions are atrocious."
Navi Pillay's criticism comes a year after Kim Jong-Un succeeded his father as the hermit kingdom's leader.