Atlanta police made six arrests and charged thirteen women with being members of a ring stretching across the US.

The victims - from China, Thailand, Malaysia, Vietnam and Korea - signed contracts with the smugglers for fees of between $30,000 to $40,000. But when they got to Atlanta they were kept under guard and forced to work in brothels in virtual slavery until they repaid the full amount.

A federal attorney, Janice Gordon, said that while the smugglers were honest with some of the women about their fate, a number of others were tricked into thinking they would be given respectable jobs.

"They thought they were coming to either be seamstresses or masseuses and found out they were to be prostitutes when they got here and they were not given the option to leave," she said.

The prostitutes proved to be extremely profitable to the organisations keeping them in captivity.

According to the authorities, one brothel alone made $1.5m in just two-and-a-half years.

A number of the women have now been arrested and deported back to their home countries but others will be much more difficult to track down after they were sent to work in brothels in different cities.