GENEVA (AP) — The United Nations migration agency says it's "deeply concerned" about some 260 Somali and Ethiopian migrants allegedly held and mistreated by criminal gangs in Libya, saying it believes that a harrowing video of them posted on social media is authentic.

The International Organization for Migration on Thursday noted the video posted June 9 on Facebook in which "hundreds of emaciated and abused Somalis and Ethiopians are seen huddled fearfully in a concrete room."

The IOM says 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 says some captives' relatives had received videos asking them to pay $8,000-$10,000 "or their child or relative will be killed."