Image caption The women were lured from Bangkok with the promise of a better life

US prosecutors say they have shut down an international sex trafficking ring in an operation stretching from Thailand to the US.

Twelve Thai nationals and five Americans were charged with illegally transporting hundreds of women from Thailand.

Their victims were forced to work as prostitutes across the US.

A US lawyer said the ring promised poor women a bright future, then "forced them to live a nightmare".

The women were driven into prostitution in Chicago, Los Angeles, Washington DC, and other cities, to pay off "bondage debts" of between $40,000 and $60,000 (£31,000 and £47,000).

"The 17 people charged in this indictment ran a highly sophisticated sex trafficking scheme," US lawyer Andrew Luger, of the district of Minnesota, said in a statement.

'Like modern day sex slaves'

"They promised women in Thailand a chance at the American dream, but instead exploited them, coerced them and forced them to live a nightmare. In short, the victims lived like modern day sex slaves."

Image copyright Getty Images Image caption The victims were forced to work in cities including Las Vegas, LA and Washington DC

Brought into the US on fraudulent visas, the trafficking victims were made to work long hours to repay the criminal gang. They were encouraged to have breast implants in a bid to make them more appealing to potential clients, and the cost of the surgery was added to their debt.

As soon as they arrived on US soil the women were trapped in massage parlours, hotels and apartments and ordered to sell sex. They were not allowed to leave without escorts, who also had sex with the victims as part of their payment.

Alex Khu, a special agent in charge of Homeland Security Investigations in Minneapolis, said the gang threatened to harm the women's families if they tried to escape.

In one case, the group sent thugs to assault a victim's relative in Thailand, breaking his bones.

US authorities believe the scheme has been operating since at least 2009.

According to the indictment, the lynchpin in the vice ring was Sumalee Intarathong - a 55-year-old woman who was recently arrested in Belgium for separate trafficking offenses there. The US plans to seek her extradition.