French President Emmanuel Macron called for an agreement on Tuesday (November 28) to evacuate Libya's "populations in danger," ahead of a European Union - African Union summit in Abidjan on November 29.
It follows international outrage at a video appearing to show African migrants being auctioned.
"It is a crime against humanity today before our eyes, it must be named, not to accuse the other, but to act with force, with vigour," Macron said, while on tour in Africa.
The meeting between the two unions, which is to be attended by more than 80 heads of state and government, was organised to discuss common strategy and avoid another "migration peak".
A CNN documentary on slavery, broadcast in mid-November, filmed not far from Libya's capital Tripoli saw the topic added to the summit's agenda.
France previously called for the UN to impose sanctions on human traffickers operating in Libya.
The Security Council has expressed horror at the footage broadcast earlier this month by CNN. France wants the chair of the UN's sanctions committee, currently in Sweden, to act.
Sweden's deputy UN ambassador, Carl Skau:
"All states have an obligation to prevent, deter, and penalize the crime of slavery. It is always prohibited and may very well amount to crimes against humanity. We condemn any such acts in the strongest terms."
Last week a group of 161 Ivorian migrants returned home from Libya under the auspices of the IOM, the International Office of Migration. Among them was Serge who confirmed that the slave trade was all too common.
"As soon as you arrive in Libya, the first thing happening is that you are taken away and you are sold. Our black brothers from West Africa, wherever you are from, a Malian, a Senegalese, or any other nationality from the West, even an Ivorian, you are sold."
The Security Council last week adopted an Italian-drafted resolution urging tougher action to crack down on modern slavery worldwide.
But people smugglers and human traffickers have been operating with impunity in Libya and have sent thousands of migrants to Europe, mainly Italy, by sea since 2014. Many have died during the voyages.