It's a scandal that any family in a continent as rich as Africa, with its vast oil and mineral wealth, should be so poor they feel forced to sell their daughter, the African Union's goodwill ambassador on child marriage said.
Globally 15 million girls are married off every year – the equivalent of the population of Zimbabwe or Mali – sometimes in exchange for a dowry or "bride price".
"It's very painful when families say we have no choice, we're so poor and that's why we married off our daughter," Nyaradzayi Gumbonzvanda told the Thomson Reuters Foundation.
"Really, can we be that poor? The extent of poverty which compels families to sell off their daughter is a wake-up call for the continent," she said on Tuesday, Day of the African Child, which this year focusses on child marriage.
Across sub-Saharan Africa two in five girls are married as children.
Niger has the world's highest rate of child marriage with three quarters of girls ending up as child brides, and nearly half of them wed before 15.
Child marriage deprives girls of education and opportunities, jeopardises their health and increases the risks of exploitation and sexual and domestic abuse, experts say.
Gumbonzvanda, a human rights lawyer from Zimbabwe, whose mother was married as a girl, said child marriage sanctioned rape and forced labour, and entrenched poverty.
"It's unacceptable that a continent as rich as Africa – with oil and diamonds, and with coltan that is found in everyone's phone – can leave its people so poor that they feel they have no choice but to marry off their daughters," Gumbonzvanda said.
"It's obscene to see ourselves in this situation. Definitely it's a scandal."
Tipping point
Campaigners warn that Africa will never prosper until child marriage ends.
"Millions of girls miss the skills, knowledge and employment prospects that would enable them to lift themselves and their families out of poverty and contribute to our continent's economic development and prosperity," said Françoise Moudouthe from Girls Not Brides, a global partnership to end child marriage.
Moudouthe said the persistence of child marriage had hindered efforts to achieve six of the eight Millennium Development Goals, including targets on education, combatting HIV/AIDS and improving maternal health.
Girls who give birth under 15 are five times more likely to die in childbirth than young women in their 20s.
Campaigners said Africa had reached a "tipping point" and that it should be possible to end child marriage within a generation with the right political will.
But they said, without action, the number of child brides in Africa could double by 2050, fuelled by population growth.
Last year the African Union launched a two-year campaign to accelerate efforts to end child marriage across the continent.
Malawi recently passed legislation on child marriage and countries including Egypt, Ethiopia, Mozambique and Zambia have launched or are developing national plans to tackle the issue.
Gumbonzvanda has been attending this week's AU summit in Johannesburg with 30 girls who were married as children. They are meeting ministers and officials to discuss solutions.
She said she did not like the term child marriage as it concealed the rape, slavery and impoverishment that happens to child brides.
"It is not a marriage when the girl is 14 and the man is 35, 40 or 70. It's a crime," Gumbonzvanda said.
