NEW DELHI • A leader from Prime Minister Narendra Modi's party, who is facing an accusation of marrying his son to an 11-year-old girl in the state of Jharkhand, has put focus on the age-old problem of child marriage, a banned "tradition" that remains a drag on a country seeking to be a global leader.

The Jharkhand president of the Bharatiya Janata Party (BJP), Mr Tala Marandi, 53, and his son Munna, who is in his 20s, both face charges under the Prohibition of Child Marriage Act, which carries a jail term of up to two years, for the marriage that took place on June 27.

While Mr Marandi has said the girl is over 18 and termed it a conspiracy by his political opponents, state child protection authorities said a preliminary investigation suggested that she was born in 2005. A court will decide on July 19 whether to give her a medical test to confirm if she is really under 18.

"According to the report, the girl is a minor. We will monitor and, if needed, we will launch investigations of our own," said Dr Manoj Kumar, a member of the Jharkhand State Commission for Protection of Child Rights.

Child marriages - girls under the age of 18 and men under the age of 21 - are illegal in India, with everyone from the priest who solemnises the marriage to those who helped with the wedding liable for prosecution. There are daily media reports of such marriages being stopped. The spread of education and awareness schemes has seen marriages for girls under the age of 15 decline by 30 per cent and for those between 15 and 18 by 13 per cent in the decade since 2000.

India still has the highest number of child marriages, with an estimated 47 per cent of girls married before they are 18, according to the United Nations Population Fund.

Ms Rajyalakshmi, now 24, was only 13 when she was married off to a man 11 years her senior in Tamil Nadu. She had her first child at 14 and her second at 18. For years, she was in an abusive relationship.

"When I got married, I didn't even know it was wrong. I feel really bad when I think of all the years when other girls my age were going to school," said Ms Rajyalakshmi, who works as a beautician and tailor and also counsels other women forced into child marriage.

She added: "A lot of things have changed since I was married off... Girls are being educated more and there is more awareness. But there are still girls like me."

Social activists said a key reason that child marriages are still taking place is the uneven implementation of the law on the ground. Data from the National Crime Records Bureau shows only 222 and 280 cases have been registered under the Act in 2013 and 2014 respectively.

Said Dr Ranjana Kumari, a women's rights activist and director of the New Delhi-based Centre for Social Research: "We are not saying arrest every single person, but make an example. If the government is seen to be strong, the whole thing will start declining."

Child marriages are common in poor communities and girls are married off early for a variety of reasons, from poverty to the idea that it will protect a girl's chastity.

Activists believe the only way to stop the practice is to create more opportunities for girls. "It is not just about policing but also about taking positive measures, creating schools, skill centres and opportunities for women," said Ms Sehjo Singh of ActionAid India.