Thirteen people have been arrested by police officers in connection with people trafficking, prostitution and money laundering.
Humberside Police raided five addresses in Hull, Grimsby and Beverley.
Three women, said by police to be victims of people trafficking - are being interviewed at a secret location.
Detectives say they believe other brothels may still be operating in the area and want members of the public to get in touch.
Det Ch Insp Dena Fleming said: "We are keen to identify any other location or brothel where this kind of activity may be taking place and we want to help other victims of people trafficking.