Smuggling of women and children to other countries as cheap and easily exploitable labour or for prostitution is a widespread problem across Africa, the United Nations Unicef agency said in a report on Friday.
Unicef said nearly all states on the continent were affected as importers or exporters, or both, in trafficking although many did not recognise its existence.
"Trafficking is among the worst violations of child rights in the world," said Carol Bellamy, Unicef's executive director.
"If we are to put an end to this brazen trade, we need courageous government leaders who will criminalise trafficking in all its forms," she declared in a comment on the 72-page report from Unicef's Innocenti Research Centre in Florence.
The report, based on studies in 53 African countries, gives no overall figures for the women and children involved. Unicef officials say the numbers fluctuate rapidly and, in Africa, almost no statistics are kept.
They also argue that even rough totals would be meaningless in an activity which can cover many types of movement of people and involves victims who have no identity papers and often do not know where they originally came from.
The report, "Trafficking in Human Beings, Especially Women and Children, In Africa," says victims from about a third of the states covered went to Europe and from a quarter to the Middle East.
Trafficking within national borders was very common, it added, and much of it happened among countries in the same sub-region of the continent.
In southern and eastern Africa, the flow was normally from the poorer countries nearer the Equator - Kenya, Tanzania and Mozambique - to the richer south, and especially South Africa.
But in western and central Africa, there was no one major magnet.
The traffic was also driven by a demand for cheap domestic and agricultural labour, for child soldiers in conflict zones, and by a growing business offering children for adoption by childless couples, Unicef said.