Here's what Interpol says about the children's work:
The children had been bought by plantation owners needing cheap labor to harvest the cocoa and palm plantations. They were discovered working under extreme conditions, forced to carry massive loads seriously jeopardizing their health... Children told investigators they would regularly work 12 hours a day and receive no salary or education. Girls were usually purchased as house maids and would work a seven-day week all year round, often in addition to their duties in the plantations.
Specially trained investigators in child exploitation and trafficking interviewed the victims with the responses providing investigators with a clearer picture of the extent of child labour in the region and potential regional networks. None of the children were aware that child labor is illegal.
With Ghana and Côte d'Ivoire producing around three quarters of the world’s cocoa, it is believed that hundreds of thousands of children are working illegally in the plantations across these two countries alone. The trafficking of children is often camouflaged by the cultural practice of placing young children with families of wealthier relatives to receive an education or learn a trade. In reality, they are often sold and their rights to education, health and protection denied. To continue tackling this trend, a second operation is scheduled for later this year in Ghana.