The U.N. human rights chief says the European Union policy of helping Libyan authorities intercept migrants on the Mediterranean and return them to Libya is "inhuman."

Zeid Ra'ad al-Hussein decried "unimaginable horrors" faced by 19,900 migrants now detained in the North African country, more than 2½ times the number in mid-September.

He appealed Tuesday to the international community to face up to the "unimaginable horrors" the detained migrants are facing.

U.N. rights monitors this month visited four facilities in Tripoli operated by Libya's Department of Combatting Illegal Migration.

Zeid, a Jordanian prince, said the monitors were shocked at the sight of "thousands of emaciated and traumatized men, women and children piled on top of each other, locked up in hangars with no access to the most basic necessities."