The United Nations migration agency has said it is "deeply concerned" about some 260 Somali and Ethiopian migrants allegedly held and mistreated by criminal gangs in Libya.
The International Organisation for Migration (IOM) said it believes that a harrowing video of them posted on social media is authentic.
It noted the video posted on Facebook on June 9 in which "hundreds of emaciated and abused Somalis and Ethiopians are seen huddled fearfully in a concrete room".
The IOM said a Somali journalist based in Turkey recorded the video call from the gang in which some migrants claimed to have been beaten.
Some alleged having their teeth ripped out and arms broken.
The agency said some captives' relatives had received videos asking them to pay 8,000-10,000 US dollars "or their child or relative will be killed".