One third of the world's child brides live in India, which also accounts for a large number of unregistered births, according to a UNICEF report.
The new report titled 'Progress for Children: A Report Card on Child Protection' says that despite rising literacy levels and legal prohibition, tradition and religious practices are keeping child marriage alive in India.
Highlighting that South Asia has more child marriages than any other region, the report points out that both India and Nepal have a high rate of child marriage involving boys, which is 10 per cent or higher.
It says more than half the world's child brides are in South Asia, which also accounts for more than half the unregistered births.
The report notes that an estimated 47 per cent of children born in 2007 who were not registered at birth are South Asian, and out of these 24 million children 16 million are from India.
"A society cannot thrive if its youngest members are forced into early marriage, abused as sex workers or denied their basic rights," UNICEF chief Ann Veneman said.
"Understanding the extent of abuses of children's rights is a first step to building an environment where children are protected and have the opportunity to reach their full potential," she added.