The 30th African Union summit concluded in Addis Ababa on Monday with a call for strengthening the African unity. Among other problems the AU has vowed to fight: the slave trade. Migrants are being snatched and sold as they make their way north. And while officials pledge action, there are few options. CGTN's Jim Spellman has more.

Last November, CNN aired these images -- humans allegedly being sold into slavery for as little as $400 in Libya.

EMMANUEL MACRON FRENCH PRESIDENT "It is a crime against humanity. It is also today one of the biggest money-making trafficking schemes and which feeds the most serious crimes and some terrorist networks."

The modern slave trade in Libya is driven by the ongoing migrant crisis. It's impossible to say how many people have been sold into slavery, but vulnerable African migrants making their way north toward Europe often rely on shadowy middlemen and criminal human traffickers.

"If your agent do not pay the driver, the driver will take you to these Nigerians and sell you to them, so if you sell one person to them, like thousand dinar, one thousand dinar."

The African Union has vowed to fight the slave trade, and Libyan officials have pledged to return those sold into slavery to their home countries.

SALAH ABU-RAGUIGAH HEAD OF DEPT. OF AFRICAN AFFAIRES, LIBYAN FOREIGN MINISTRY "The Ministry expresses its rejection and denunciation of such inhumane practices which are contrary to the culture and heritage of the Libyan people."

But Libya and other African countries have limited means to fight the slave trade, especially in largely lawless areas controlled by local militias. The UN has returned more than 13-thousand migrants to their home countries since 2015 and has enacted a so-called "Libya Action Plan" to bring political stability to the North African nation, but many analysts say the international community must play a bigger role.

Nii Akuetteh is a longtime Africa analyst.

NII AKUETTEH AFRICA ANALYST "When we are talking about the international community we are talking about the United States and the Europeans. They are the 800 pound gorilla in the room, and so if the U.S. and the Europeans want something good to happen it will happen."

Akuetteh says Europe must take in more migrants.

"Europe has a terrible record in Africa from the slave trade to colonization to apartheid to satellite regimes. Europe has been exploiting Africa for 600 years and my opinion as an African is how they dare say a few Africans can't come there."

JIM SPELLMAN WASHINGTON DC "To truly stop the slave trade and the migrant crisis, many experts say something must be done to address the root causes of migration including poverty, a lack of security and political instability. Jim Spellman, CGTN, Washington."