The Nigeria Police force has rescued 300 people they say were locked in a rice-processing factory and forced to work throughout a coronavirus lockdown BBC reports.
From the end of March, the men were allegedly not allowed to leave the mill in the northern city of Kano.
The workers were promised an additional $13 (£10) a month on top of their $72 monthly salary – those who did not accept were threatened with the sack.
Five managers at the Indian-owned mill have been arrested.
The company, called Popular Farms, has not responded to BBC requests for comment.
Police spokesman Abdullahi Haruna told the BBC that the plant had now been shut down and the owners were being investigated for “holding the men against their will”.
Some of the men say were forced to work most of the time during their incarceration, with little food