Thirteen-year-old Opura Khatun from Dum Dum agreed to take up a job in Esplanade on the suggestion of a relative last August. She was told to board a train and ended up in Delhi, where she was sold for Rs 6,000 to a tout.

After a few days in a brothel, Opura was sold again for Rs 12,000 and taken to Bangalore. A few weeks ago, she was rescued and is now back in the custody of a home in Calcutta.

Around 3,000 minor girls are sold every year. A few hundred come back, but are never seen again.

Calcutta has become a hub for human trafficking, admits the state government, with thousands of minors being smuggled through town every year. Police interrogation of touts and rescued girls has revealed a growing problem.

?The rising number of cases is alarming? We do have a mechanism in place to catch touts and rescue victims,? said P.K. Agarwal, principal secretary, social welfare department.

An intelligence branch report reveals that girls between seven and 18 years, from North and South 24-Parganas, Murshidabad and Nadia are smuggled out of the city. They are mainly sent to work in prostitution rings in the Andamans, Mumbai (from where they are sold all over the country) and West Asia, especially Saudi Arabia. Some have also been sold in Kashmir.

A study conducted by Centre for Communication and Development (CCD) traced the experiences of Sonagachhi girls. ?One had travelled to London, another was taken there via Cambodia. Others spent three months each in Thailand and the Philippines. They were sold by touts for anything between Rs 7,000 and Rs 20,000,? said Swapan Mukherjee, secretary, CCD.

Calcutta is home to over 30,000 Nepalese girls who have been smuggled into the country over the past decade, sneaked into Calcutta via Kathmandu and Siliguri.

Several hundred girls also come from Madhya Pradesh and Chhattisgarh.

Young boys, too ? about 7,000, according to modest estimates ? are trafficked through Calcutta. Most are from Murshidabad, North and South 24-Parganas and Nadia.

?They are sold for between Rs 2,000 and Rs 5,000 and are mostly forced into gold and zari workshops in Gujarat and Mumbai,? said a senior intelligence branch official.

Brick kilns and tile-manufacturing units also forcefully employ boys aged between seven and 16, often from Jharkhand and Madhya Pradesh.