Five Nigerians were among the 35 women captured by the Islamic state fighters in Sirte, Libya and turned into s*x slaves for several months.
The Nigerians, including two children and 28 Eritreans were recovered by Libyan forces and then made to face another spell of detention in a Misrata prison since last December.
Reuters said the group escaped from Sirte, a former Islamic State stronghold in central Libya, while forces from the nearby city of Misrata battled to oust the militants late last year.
Some of the women were on their way to Europe when Islamic State fighters kidnapped and held them as s*x slaves.
After they escaped from Sirte, they were investigated for possible ties to the group and held for several months in a Misrata prison.
Reuters has documented how Islamic State used enslaved refugee women to reward its fighters.
In stories published last year, the women recounted how the group forced them to convert to Islam and sold them as s*x slaves.