UNITED NATIONS (AP) — U.N. Secretary-General Antonio Guterres is calling for an immediate investigation into the reported sale of African migrants in Libya, saying transactions may amount to crimes against humanity.

Guterres said Monday that "slavery has no place in our world and these actions are among the most egregious abuses of human rights."

The former U.N. refugee chief said he was "horrified" at video footage, broadcast on CNN, of the bidding and sale of migrant men seeking a better life.

Guterres called for the perpetrators to be brought to justice and said he has asked appropriate U.N. bodies "to actively pursue this matter."

He said migration must be addressed "in a comprehensive and humane manner" and should include a crackdown on smugglers and traffickers.