Amnesty International on Friday called on Yemen's Houthi rebels to release model Intisar Al Hammadi and scrap plans to conduct a so-called virginity test.
Lawyers for the 20-year-old woman say the Houthis intend to subject her to the ordeal in the next few days.
The procedure usually involves someone digitally penetrating a woman without consent to determine whether her hymen is intact – an unreliable and unscientific method of determining whether a woman has had sexual intercourse.
"Yemen's Houthi de facto authorities must immediately halt all plans to subject Intisar Al Hammadi to forced virginity testing," Lynn Maalouf, Amnesty International's deputy director for the Middle East and North Africa, said.
“She is being punished by the authorities for challenging the social norms of Yemen’s deeply patriarchal society, which entrench discrimination against women.”
Criticising the Houthi de facto authorities' "deplorable" track record of arbitrary detentions, the human rights group said there were no legal grounds to prolong Ms Al Hammadi's detention.
The Houthis arrested the model and actress at a checkpoint in Sanaa in February.
Amnesty said Houthi authorities coerced confessions on charges related to prostitution and drug offences from Ms Al Hammadi, after interrogating her while blindfolded, and physically and verbally abused her while hurling racial slurs.
Ms Al Hammadi frequently appears in photographs without a headscarf, drawing considerable backlash in conservative Yemeni society.
Born to a Yemeni father and an Ethiopian mother, Ms Al Hammadi helped support her family prior to her incarceration, including her 12-year-old brother who is disabled.
According to her lawyers, interrogators would wake her up in the middle of the night and drive her to various houses to ask if she had worked in them as a prostitute.
Amnesty also noted that in April, a gunman threatened Ms Al Hammadi's lawyer in the case.