A New York-based campaign group says Tanzanian workers in Oman and the United Arab Emirates are facing abuse, including unpaid salaries and excessive working hours.
One Tanzanian domestic worker told Human Rights Watch she had to work 21 hours a day and had been sexually abused.
The rights group said a major problem was the visa sponsorship system whereby workers are tied to their employers.
Gulf countries are increasingly turning to East Africa as a source of labour as Asian countries take more steps to protect domestic workers who migrate to the region.
