It was an upstairs bedroom: a double bed, massage table and, in the dim red light, a "beautiful" curtain on the rear wall. A middle-aged woman pulled the curtain aside to reveal twin doors. Low in one door a hole had been cut, and beyond was darkness.

The girl with her was ordered through the hole, into a storage area which was packed with cardboard boxes, and another room with mattresses on the floor. Weeks later, police would find the hole in the wall, which, unbeknown to passers-by, created a link between the brothel and the building next door.

The goings-on in those two buildings are just one example of something evil under Sydney's nose.

Forget the red-light seaminess of Kings Cross. These brothels, some of them licensed by local councils, exist in Sydney's residential heartland: Annandale, Marrickville, Rozelle, Strathfield, Surry Hills, Homebush, Penrith and Ryde.

Although the extent of sexual servitude in Australia is unknown, more stories are emerging of young Asian women being lured on false promises, only to end up working as sex slaves in a strange land, with little English, no passports and no freedom.

THE 20-year-old Thai student thought she was coming to Australia as a waitress, but said that 24 hours after arriving, she was put to work. Three Indonesian girls were luckier. Before being put to work they escaped from an inner-west red-brick unit and, in the middle of a winter's night, ran through the back streets begging motorists to stop.

Before escaping they had allegedly been under the tutelage of a woman identified by police as one of seven people charged in Sydney and Melbourne on sexual slavery charges.

The women say they are either duped or agree to work as prostitutes, but once they arrive in Sydney their passports and airline tickets are confiscated, they are confined and forced to pay "debts" - on average, about $45,000. Some, like the Thai student, believed that $200,000 changed hands.

One Indonesian woman, a prostitute who spent time in another inner-west brothel, was blunt: "This was not what I had expected. I would never have come to Australia if I was to be treated like this. I felt locked up like an animal, had no freedom ... I felt totally trapped and unable to think of a way to escape."

The girls are a commodity. The brothel owners take about 60 per cent of the half-hourly rate of $120-$130; the rest goes towards their debt. The girls keep their tips. "Just put up with it and you will finish your debt within one year," the Thai student recalled being told by another girl.

THE trail to Sydney for escapees "Eti" and "Yosien" started in April last year when they travelled from their small Indonesian village to a neighbouring village to consult a soothsayer. One wanted guidance about caring for her sick mother; the other advice about a business opportunity.

As fate would have it, the psychic had died, and the girls were sent on a bumpy bus journey to another village. A man identified as Sutikno told them of their good fortune: they could make 10 million rupiah a month ($1509), plus tips, working in a restaurant in Australia.

When Eti was taken to the airport in Jakarta, she was met by "the boss" - a Chinese-Indonesian middle-aged man - who allegedly handed her a false passport, visa and boarding card. The immigration officer let her through, but kept the $160 bribe hidden inside the passport. He joined her on the flight.

Yosien had made the journey two weeks earlier. Instead of a restaurateur, she was met by a man who took her passport, allegedly telling her she was going to work in a sex shop and would have to work 400 hours in this arrangement to pay him back. He added that if she was not choosy, she would be able to pay the debt off in three months.

The girls frequently have no idea of the size of the debt, and it bears little relation to the actual outlay of the traffickers. When they arrive the girls work off the debt to the brothel owner, who pays the traffickers and agents who recruit the girls.

Financial records found during an investigation by the Australian Federal Police and their Thai counterparts into the most recent instance of sexual slavery show the owners of two suburban brothels transferred $48,000 in three months to the Bangkok account of a woman trafficker.

The Thai student was also recruited by a woman, whom she knew as "Aunty Pui". Pui allegedly said she could earn $150 a week at the restaurant, and, while living free on the premises, could repay the airline ticket from her wages.

After their arrival, the girls are groomed and tarted up with trips to Paddy's Markets. The Thai student said she was shown a black see-through dress and new red G-string when she arrived at the Annandale brothel.

"All the windows had bars on them and I couldn't get out ... I sat on the sofa and cried. I thought if I was a virgin I would never do it, I would prefer to kill myself." Her first customer had a shower. "I explained I did not want to have sex with him, he didn't say anything but continued to have sex with me. I cried during the whole time I was in the room with him." She was anally raped by another customer.

After a week she was allegedly sent to another brothel owner. "There were 15 girls who lived at the [inner west] house - three bedrooms and five girls each room. Jack [the minder] sleeps in another room. Jack drives all the girls to the brothels. Every day I worked 9 to 4am the next day." She would be told how much she had to make every day: "It varies from $400-$1000," she told police.

The student was given $20 for food for the week. Jack's shopping trip netted her canned tuna, six eggs, four packs of noodles, a bottle of milk and some oranges.

Another girl, also duped into thinking she was to work in a restaurant, found the penalty for refusing to work was to go hungry. "If I didn't work I wouldn't get any food ... The last day I had any food was midday two days earlier," she told police.

THE trafficking puzzle is being investigated by Operation Tennessee, an operation run by the federal police and Department of Immigration. Legislation introduced four years ago provides for jail terms of up to 25 years for those involved in sexual servitude.

Kathleen Maltzahn, the director of the Melbourne-based advocacy agency Project Respect, said those involved in the trade of sex slaves sometimes include women who had originally been trafficked. Girls tended to be more trusting of women, which made it easier for them to be duped.

"In the past people really couldn't believe it was happening. People now are more aware and are picking up the signs, from police through to customers," she said.

Maltzahn believed the cases now coming before the courts showed the state and federal government agreement last year to combat trafficking was working. But while the visa protection arrangements had improved, they were still deficient. "We need to look at how we support women to come forward, and while we have a witness support program rather than a victims support program it's hard to do that," she said.

Escape can be daunting, but not impossible. The Thai student was rescued by police after calling 000 when the brothel's reception was briefly unattended. Another Thai girl, "Vivian", who was allegedly locked up after hours in a brothel at Strathfield, rang a customer, begging him to call the Department of Immigration.

Even working prostitutes see an Immigration raid as the only way out. "Cherry" arrived in April last year and saw 160 clients before she was picked up the next month as part of Operation Tennessee. All she'd seen of Melbourne was the one-bedroom high rise she was locked in with five other girls, and the daily chauffeured car journey to the brothels. The one night out at karaoke and three shopping trips had all been under escort.

"The girls and I hoped that we'd get caught by Immigration, as it was the only safe way we could see to get home," she said.