DAKAR, Senegal – The African Union and member states will repatriate more than 15,000 migrants stranded in Libya by the end of the year amid outrage over recent footage that showed migrants being auctioned off as slaves, the AU’s deputy chairman said Tuesday.

Between 400,000 and 700,000 African migrants are in dozens of camps across Libya, often under inhumane conditions, AU Commission chairman Moussa Faki Mahamat told a summit of European and African leaders last week. The International Organization for Migration says more than 423,000 migrants have been identified in the chaotic North African country, most of them from impoverished countries across sub-Saharan Africa.

Libya’s modern-day slavery came to international attention after the CNN footage showed migrants being auctioned off for as little as $400. Thousands of migrants make their way to Libya in hopes of eventually reaching Europe via the Mediterranean, often facing desertion and inhumane treatment by smugglers.

The voluntary evacuations from Libya of more than 15,000 migrants will take place in cooperation with the International Organization for Migration, African Union deputy chairman Kwesi Quartey said Tuesday. The continental body will help to issue emergency travel documentation and facilitate travel, he said. He did not specify which countries’ migrants would be sent home.