An IS commander told CNN on Wednesday that the abducted women and children were taken from Sinjar to Mosul when the militants attacked the town last week.
"At that time, they took Yazidi women and children, and I can confirm those women and children have entered Mosul... The Islamic State is taking this opportunity to call them to Islam."
If confirmed, IS militants are using a tactic previously reported by survivors of the fighters separating women and children from male relatives.
IS militants last week attacked Sinjar, forcing tens of thousands of residents to flee and seek shelter on the nearby mountaintop. With militants encircling the base of the mountain and the trapped residents running low on food and water supplies, the security and humanitarian situation prompted U.S. President Barack Obama to authorize humanitarian and military action.
Obama announced on Aug. 7 that "American aircraft have begun conducting humanitarian airdrops of food and water to help these desperate men, women and children survive." He also authorized the use of targeted airstrikes to thwart advances by the Islamic State.