The Tanzanian government has banned up to 70 employment agencies that send women to countries in the Middle East to be housemaids.
It comes after complaints that women who travel from Tanzania to the Middle East for work are being mistreated.
Some are forced to work in jobs they didn't apply for, including the drugs industry, says the BBC's Sammy Awami.
Job agencies in Oman have previously stopped recruiting Tanzanian workers, reports the Times of Oman.
Seperatus Fella, secretary of the government's Anti-Trafficking Secretariat announced the ban.
"Most of these girls and boys are subjected to commercial sex or work as domestic servants and barmaids, with some sent on forced labour in factories, farms and mines under very poor conditions," Mr Fella told the Reuters news agency.
Tanzania provides the largest number of housemaids from African countries to Oman, Tanzania's The Citizen newspaper reported in 2014.
The Times of Oman explains that Omani employers prefer Tanzanian domestic workers because Swahili is widely spoken in Oman.
But in 2014 the newspaper said five job agencies in Oman stopped recruiting Tanzanian workers following complaints from both domestic workers and their employers ranging from violence to child abuse.