It's about 8 pm in the humid heart of Mumbai, the home of Bollywood. Cautiously, I walk down the lane of one of the subcontinent's biggest red light districts, Kamathipura Road, right next to the Mumbai Central railway station. My Japanese photojournalist friend Q Sakamaki tags along.

We walk past several vegetable vendors, grocery and pan (betel leaves) shops before we realize that we are in Kamathipura. Young girls and women, heavily made up, are lined up outside the brothels they live and work in. Loudspeakers blare out the recent Bollywood hit number 'Kajrare'.

We scan the faces of these girls and women. They appear to represent practically every state of India and every country in the subcontinent. A pimp follows us and says in English, over and over - "Good item girls, sir. Good items, sir. Nepali girls, Bengali girls! Only Rs 300, sir!" We walk on unheeding, and a second pimp pops up. Then a third one. We are overtly irritated, but they seem adamant on getting custom from us. We try to walk into the brothels, take pictures and ask the women about their lives and history. This, however, is far from easy.

We have to make do with brief conversations, observations and quick photographs. Then we see a dark-complexioned woman in her thirties standing outside a beauty parlor. Flanked by two other women, she is inviting prospective clients. The crowded, smelly street is dirty but colorfully lit-up. When we approach her, she says firmly, "No photos, no photos!"

"Namaste! Tapain lai kasto chha? (How are you doing?)" I ask in Nepali. Fifteen years in sex work, far away from home, these three women still wear their ethnic jewellery and clothes. They are from the hills of Nepal. The dark-complexioned woman is talkative. "We work on the streets every night to make our survival money." She was tricked, she reveals, and then sold here - traded by her boyfriend into two years of bondage and then prostitution for just a couple of thousand rupees. Is she planning on returning home, though? Speechless, she scans the street for some time and replies, "I will wait for my 'kaal' (death) here."

A quick walk around Kamathipura and conversations with some women who work there make it clear that much of this infamous red light area is made up of South Asian women - a majority of them Nepali - who have been sold into bondage and sex slavery. A survey conducted 15 years ago by Samyukta Nepali Mahasangh, a Mumbai-based organization of expatriate Nepalese, puts the number of Nepali women in the 350-odd brothels at over 18,000.

Other big cities - like Pune, Delhi and Kolkata - are no different. According to a study published a decade ago, there were over 200,000 Nepali women involved in the sex trade in India in the mid-1990s. The study estimated that every year an additional 7,000 women are trafficked from the hills of Nepal to India.

Some activists say that the HIV/AIDS scare in recent years may have led to a reduction in the number of brothels in Mumbai. But, clearly, the problem looms large still.

Experts who have been closely monitoring the sex industry say there have been paradigm shifts. Open red light areas have moved to clandestine brothels flourishing in small towns and farmhouses in suburbs. There has also been a shift in the Nepal-to-India route, and many women are now trafficked to other countries in West and East Asia via India.

A third - and worrying - shift is that trafficking is now moving beyond its 'conventional' poaching grounds, such as Sindhupalchok and Nuwakot districts, to new areas like Rolpa and Rukum, says Renu Rajbhandari of Kathmandu- based Women Rehabilitation Centre (WOREC). Thanks to the "open and porous" Nepal-India border, she says, "many more girls from previously unheard-of places in Nepal are now in brothels across India."

Even minors are not spared. Police and NGOs in Delhi and Mumbai have rescued dozens of minor girls in recent raids. Yet, there are no signs of the trade in women and children tapering off. Two months ago, 32 Nepali girls were rescued from Mumbai brothels. They were later handed over to a Nepali NGO.

Although international laws and conventions strongly condemn trade in human beings and trafficking in women and children, the multi-million dollar cross-border trade continues. A recent study has blamed the "economic forces that drive trafficking from Nepal - the demand of the client, and more importantly, the demand of the brothel owner."

After the "abduction or purchase of girls in Nepal by traffickers and the transportation of girls to the brothels of Mumbai or Kolkata", the girls spend their first two to ten years in slavery and debt bondage, according to a study by Terre Des Hommes, Nepal.

The study also reveals that "those who have been given their freedom are unable or unwilling to return to Nepal, and continue their lives as sex workers". Experts blame social stigma and the stigma around HIV/AIDS. The bottom-line is that once these women are trapped in the flesh trade, there's little getting out of it.