Bharatpur: India has four million prostitutes and their number is likely to swell to 10 million in a few years, says a nationwide study conducted for the department of women and child development.

About 35 per cent of prostitutes forced into the trade are below 18 years of age, reveals the study conducted between 2002 and 2004.

"The worst thing is that most of the girls are between 12 and 15 years," said K.K. Mukherjee, who conducted the study.

"About 35 per cent were below 18 when they entered sex trade. The number of child prostitutes is on the rise due to various socio-economic and cultural factors," he added.

The study is based on interviews of about 9,500 prostitutes in all states.