Thousands of Europe-bound migrants who were intercepted at sea and returned to Libya this year have been forcefully disappeared from unofficial detention centres run by militias allied with the Government of National Accord in the capital, Tripoli, Amnesty International said.
Libya, which descended into chaos following the 2011 uprising that toppled and killed long-time dictator Muammar Qaddafi, has emerged as a major transit point for African and Arab migrants fleeing war and poverty to Europe.
Most migrants attempt the perilous sea crossing to Europe in ill-equipped and unsafe rubber boats. In recent years, the EU has partnered with Libya's coastguard and other Libyan forces to stop the flow of migrants across the Mediterranean, with thousands intercepted and turned back.
Amnesty said about 8,500 migrants, including women and children, were returned to Libyan shores between January 1 and September 14 this year. Since 2016, an estimated 60,000 men, women and children have been captured at sea and taken back to Libya, it said.
"The EU and its member states continue to implement policies trapping tens of thousands of men, women and children in a vicious cycle of abuse, showing a callous disregard for people's lives and dignity," said Diana Eltahawy, Amnesty's deputy regional director.
Thousands have been subjected to enforced disappearances after being taken to unofficial detention centres in western Libya, including the so-called Tobacco Factory in Tripoli, run by a government-allied militia, Amnesty said.
There, the migrants and refugees face a "constant risk" of being abducted by armed groups and traffickers.
They are "trapped in a vicious cycle of cruelty with little to no hope of finding safe and legal pathways out", Amnesty said.
"Some are tortured or raped until their families pay ransoms to secure their release. Others die in custody as a result of violence, torture, starvation or medical neglect."
Ms Eltahawy urged the EU to "completely reconsider" its co-operation with Libyan authorities and make "any further support conditional on immediate action to stop horrific abuses against refugees and migrants".
In eastern Libya, authorities expelled more than 5,000 refugees and migrants this year, citing their alleged carrying of "contagious diseases" among other reasons.