French president Emmanuel Macron has announced that the European Union and African Union will launch "concrete military and policing action" to rescue African migrants enslaved in Libya and arrest human traffickers.

The development came as the EU pledged a Marshall Plan for Africa of €44 billion at a summit dominated by outrage over slave auctions in Libya of migrants sold "like goats".

The furore over illicit slave auctions, highlighted in a recent CNN report, was thrust to the top of the agenda among the 83 heads of state from the EU and Africa gathered in Abidjan, Ivory Coast, for a two-day summit.

Speaking after talks on Wednesday night, Mr Macron said that the leaders of Libya, France, Germany, Chad, Niger and other countries along who the UN, had "decided on an extreme emergency operation to evacuate from Libya those who want to be".

The evacuations would start "in the coming days or weeks".

"Libya has reaffirmed its agreement to identify camps where scenes of barbarity have been identified," he went on. "President Sarraj has given his green light for access to be assured."