The United Nations on Friday accused the European Union of "turning a blind eye" to the brutality faced by migrants held in Libya, and urged "serious action" to protect them.
"Some migrants die of thirst, hunger or easily-cured illnesses, some are tortured or beaten to death while working as slave labour, others are just casually murdered," UN human rights chief Zeid Ra'ad Al Hussein said.
Zeid detailed these and other abuses - including the rape of women "in some cases, every night" - that hundreds of thousands of migrants are suffering at the hands of authorities in Libyan detention centres in the country.
He said their situation had been "appalling" during dictator Moamer Kadhafi's rule but had turned "diabolical" since his ouster.
Italy and the European Union have been financing, training and providing aid to Libya's coastguard to stop smugglers from taking migrants and refugees in flimsy boats across the Mediterranean to Europe.
Migrants are then sent to detention centres.
The number of migrant arrivals in Italy in July was down dramatically against a year ago, suggesting efforts to train and better equip the North African country's coastguard could already be having an impact.
But Zeid said such efforts -- including the plan by European and African leaders last month to prevent people from crossing the Mediterranean -- are a "failure" because they do not deal with the "human calamity".
His comments echoed those of medical charity Doctors without Borders (MSF) made a day earlier.
MSF president Joanne Liu on Thursday published an open letter describing "the horrific situation" for refugees and migrants in detention centres she visited last week.
Libya's detention of migrants "must be named for what it is: a thriving enterprise of kidnapping, torture and extortion," she wrote in a letter to European governments.
Zeid said he agreed with Liu's assessment.
"I fully support her analysis" and "share her disgust" at what she "describes as the 'cynical complicity' of those who support returning migrants to Libya while turning a blind eye to what is going on there," he said.
He called for "serious action" to protect the migrants, adding: "We should not continue to avert our eyes from this brutal reality".
