A new report says that since the mid-1990s more than 5,000 women have been sent to South Korea by international traffickers and forced into prostitution. The report, by the Geneva-based International Organization for Migration, says most of the women are sent to the country to provide sexual services for American servicemen stationed there.

The author of the study, June Lee, says the problem in South Korea may appear small when compared to the tens of thousands of women who are forced into prostitution from the countries of the former Soviet Union. But she says the problem is growing in South Korea and the current estimate of 5,000 women forced into prostitution is probably an underestimation.

"We do not know how many more are there trapped in this horrible situation," said Ms. Lee. "Therefore, regardless of the size, there are things to be done in that way. I would say this is something people should look into."

The report by the International Organization for Migration says the women mainly come from the Philippines and the former Soviet Union. It says most of them enter South Korea on entertainment visas that do not allow for prostitution.

The sex workers interviewed for the study describe how they were recruited by agents and given false contracts to work as bar staff and entertainment hostesses. Instead, they say they ended up as virtual sex slaves.

A spokesman for the International Organization for Migration, Chris Lom, says the women live under terrible working conditions. Their passports are taken away from them, their salaries are withheld, they are abused and illegally confined.

"One of the more interesting aspects of the report is the fact that bars located near U.S. military bases are the largest employers of Filipino women recruited primarily because they speak English and are admitted to South Korea on E-6 entertainment visas," he said. "Clearly, a lot of these women are duped into going to South Korea to work in areas other than prostitution."

Last year, the U.S. government named South Korea as one of 23 countries that did not meet the minimum standards for combating human trafficking. The Seoul government has called the U.S. report inaccurate.

But the author of the report, June Lee, says that since the State Department report was published, the South Korean government has intensified efforts to prosecute traffickers.