A representative of the relatives said they wanted the 20 women to be released as soon as possible because the case against them had been finalised by a court order for them to pay fines.
NHRC member Angkhana Neelapaijit said she would speak to the relevant police investigators and the Immigration Bureau.
She said that if the women were being detained so they could be witnesses in a human-trafficking case, she would ask the authorities to provide them with appropriate care.
She said she would also ask to visit the women to find ways to help them.
The raid by Interior Ministry officials on June 7 on the parlour resulted in 121 sex workers, including at least 15 minors, being rounded up, while five employees were arrested.
The raid allegedly also uncovered logbooks detailing kickbacks to different police agencies and other officials.
The whereabouts of the parlour’s owner Prasert “Ko Luck” Sukkhee, 58, and manager Sommai Patsingh, 45, who were charged with human trafficking, engaging minors in prostitution and harbouring undocumented migrants, remain unknown.