The top human rights official at the United Nations on Monday urged for an international investigation into human rights violations in North Korea, where as many as 200,000 prisoners are thought to be tortured, raped and treated as slaves in labor camps.

"Because of the enduring gravity of the situation, I believe an in-depth inquiry into one of the worst - but least understood and reported - human rights situations in the world is not only fully justified, but long overdue," Navi Pillay, the U.N.'s highest commissioner for human rights, said in a statement.

She called for an international probe into North Korea's human rights violations --one that was approve by the United Nations but carried out by independent investigators.

Pillay cited figures by human rights organizations that estimate around 200,000 people are held in political prison campus where they are subject to "torture and other forms of cruel and inhumane treatment, summary executions, rape, slave labor and forms of collective punishment."

These activities "may amount to crimes against humanity," the former International Criminal Court judge said.

There was hope that the new leadership of Kim Jong-un would bring "positive change" in regards to human rights in the reclusive country, said Pillay, but "we see almost no sign of improvement."

Pillay pointed to "atrocious" living conditions in the prison camps that had scarce food, little to no medical care and lack of clothing.

"One mother described to me how she had wrapped her baby in leaves when it was born, and later made her a blanket by sewing together old socks," Pillay said, adding that she found survivor testimonies "extremely harrowing."

She also said the death penalty was often applied for minor offenses and overall without any judicial processes.

Prisoners who try to escape face execution, torture and further incarceration, usually with their relatives sharing their punishment, said Pillay. North Korea has also abducted South Koreans and Japanese nationals over the years, she added.

North Korea's mission to Geneva received a copy of the report Monday but did not immediately respond.

In 2012, the Human Rights Council and United Nations General Assembly passed resolutions condemning North Korea's human rights record.

Human rights advocates are urging Japan to sponsor a resolution at the upcoming Human Rights Council in March that would call for an international inquiry into North Korea.