NEW DELHI, India (CNN) -- Around 1.2 million children are believed to be involved in prostitution in India, the country's federal police said Monday.

Ashwani Kumar, who heads the Central Bureau of Investigation (CBI), told a seminar on human trafficking, that India occupied a "unique position" as what he called a source, transit nation and destination of this trade.

India's home secretary Madhukar Gupta remarked that at least 100 million people were involved in human trafficking in India.

"The number of trafficked persons is difficult to determine due to the secrecy and clandestine nature of the crime.

"However, studies and surveys sponsored by the ministry of women and child development estimate that there are about three million prostitutes in the country, of which an estimated 40 percent are children," a CBI statement said.

Prostitution in pilgrim towns, exploitation through sex tourism and pedophilia are some of the "alarming trends" that have emerged in recent years in India, it noted.

Authorities believe 90 percent of human trafficking in India is "intra-country."