UN criticises EU policy in Libya as 'inhuman'

"The suffering of migrants detained in Libya is an outrage to the conscience of humanity," he said.

The EU has helped broker deals with Libyan authorities as part of a broader plan to prevent people from leaving the country.

It includes, among others, training the Libyan coast guard to take migrants and refugees from the sea and then returning them to the war-torn country.

Many but not all are then sent to detention centres, which are often ruled by armed militia groups.

The EU's naval operation, Sophia, as of earlier this month has trained some 142 Libyans.

A first training package included 93 Libyans, which spent 14 weeks on board the Italian ship San Giorgio and the first two weeks on board the Dutch ship Rotterdam.

Another 20 senior officers at the rank of captain or commodore were trained in Greece. Malta hosted 20 trainees and a module in Italy has been started for another 66 personnel.

The Libyan coast guard has since intercepted almost 19,000 people since the start of the year until October.

Those interceptions were supposed to take place within Libyan territorial waters but charity rescue boats say the coast guard is also operating in international waters.

German-based rescue ship Mission Lifeline said in late September the Libyan coast guard fired shots, boarded it, and demanded they handed over the people it had rescued at sea.

Libya's department of combating illegal migration (DCIM) says some 19,900 people are held in detention centres as of early November, up from around 7,000 in mid-September.

The spike is due in part to the thousands of people left stranded in the smuggling hub city of Sabratha following fighting among rival Libyan militia factions in October.

Both the EU-funded International Organisation for Migration (IOM) and the UN refugee agency (UNHCR) at the time stepped in to help the migrants. Many were sent to detention centres.

The same centres, which also house women and children, are ripe with abuse, including rapes and murders.

"The international community cannot continue to turn a blind eye to the unimaginable horrors endured by migrants in Libya," said Hussein.

He noted that efforts to improve the conditions in the detention centres was not enough and that more needed to be done to ensure the protection of migrant's human rights.

Similar comments were made earlier this year by the president of Doctors without Borders (MSF), a medical NGO, Joanne Liu, who accused the EU of "feeding a criminal system of abuse" by forcing migrants back to Libya.

The EU has in the past said that it is working to protect migrants in Libya.

The EU over the summer set aside some €46 million to boost Libya borders and step up support for the Libyan border and coast guard.

The EU backed programme, implemented by the Italians, includes giving the Libyans both training and equipment in terms of maritime surveillance and rescues.