Amnesty International says Burmese migrants working in Thailand are subject to abuse and exploitation at the hands of employers, smugglers and local police.
The London-based human rights group interviewed 115 Burmese immigrants for a report released Wednesday.
Amnesty says the immigrants are paid well below the Thai minimum wage, live and work in unsafe and unhealthy conditions, and are at risk of arbitrary arrest and deportation.
The report also says the workers are targets of extortion by law enforcement officials.
Hundreds of thousands of Burmese have fled to Thailand to escape armed conflict between ethnic groups and the military.
Bangkok has established a registration system to keep track of migrant workers, but tens of thousands of workers are believed to be undocumented.
Information for this report is provided by AP and AFP.