Three people were arrested on suspicion of human trafficking offences in Shirebrook yesterday.
A 17-year-old man and two women aged 33 and 36 were arrested by investigators from The Gangmasters and Labour Abuse Authority (GLAA) at a residential address in the town on Wednesday morning.
All three suspects, who are Romanian nationals, have been released under investigation pending further enquiries.
Four Romanian women in their 30s were identified as potential victims and have been rescued and safeguarded.
GLAA investigators also searched properties in Shirebrook and Mansfield as part of the investigation.
The operation was conducted with police officers from Derbyshire and Nottinghamshire together with partners from Bolsover and Mansfield District Councils.
GLAA Senior Investigating Officer Dave Powell said: “We are extremely grateful for the support of our police and council partners whose hard work alongside us has resulted in a successful operation.
“Continued partnership working like this sends a clear message to offenders that we have a zero tolerance approach to this sort of criminality. We will keep working together to protect vulnerable workers and do all we can to eradicate modern slavery.”