“They flogged me, they slapped me, they beat me while I was on the phone with my mother so she could hear me cry,” said Ishmael Konte, a 25-year-old from Sierra Leone, recounting his time in southern Libya.

Libya, the biggest jumping-off point for migrants trying to reach Europe, is now home to a thriving trade in humans. Unable to pay exorbitant smuggling fees or swindled by traffickers, some of the world’s most desperate people are being held as slaves, tortured or forced into prostitution.

Their deteriorating plight raises questions about European Union agreements to stem the flow of migrants. Under these deals, Libya was promised more than $225 million to enforce stricter border controls and maintain migrant assistance centers that respect “international humanitarian standards.” Last week, Libya’s Western-backed government asked European leaders in Brussels for more money to cope with the crisis.

But instead of getting better treatment, migrants found at sea are being returned to Libya to face more exploitation and violence.