African refugees attempting to migrate through Libya to Europe are being captured and sold in public slave markets, the International Organization for Migration (IOM) reports.

Word of the slave markets reached the organization after survivors were able to pay their ransom or escape by other means.

Separate from the migrant crisis engendered by the Syrian Civil War, massive numbers of Africans from sub-Saharan Africa are risking their lives to migrate through Northern Africa and on into Europe. Libya, for years a lawless region with many areas governed only by militia groups, has become the main hub for migrants desperate to reach Europe.

One migrant, a Senegalese man who was held for months, described the conditions he and hundreds of others endured once they were captured by armed groups as they made the trek into Libya. Typically, once they become prisoners, they are forced to call their families and demand ransoms for their release. While they speak to their families over the phone, their captors beat them, so that their families can hear them endure the torture.