The European Union's policy of helping the Libyan authorities intercept migrants in the Mediterranean and return them to "horrific" prisons in Libya is "inhuman", the United Nations said Tuesday.

"The suffering of migrants detained in Libya is an outrage to the conscience of humanity," the UN human rights chief Zeid Ra’ad Al Hussein said in a statement, which blasted "the European Union's policy of assisting the Libyan Coast Guard to intercept and return migrants in the Mediterranean (as) inhuman."