'Virgin, beautiful, 12-year-old girls on sale' – Islamic State's ad on WhatsApp, Telegram

On a chat on WhatsApp, an ISIS militant offers a woman and her children for sale.

Khanke: The advertisement on the Telegram app is as chilling as it is incongruous: A girl for sale is "Virgin. Beautiful. 12 years old.... Her price has reached $12,500 and she will be sold soon."

The posting in Arabic appeared on an encrypted conversation along with ads for kittens, weapons and tactical gear. It was shared by an activist with the minority Yazidi community, whose women and children are being held as sex slaves by the extremists.

While the Islamic State group is losing territory in its self-styled caliphate, it is tightening its grip on the estimated 3,000 women and girls held as sex slaves. In a fusion of ancient barbaric practices and modern technology, IS sells the women like chattel on smart phone apps and shares databases that contain their photographs and the names of their "owners" to prevent their escape through IS checkpoints.

The fighters are assassinating smugglers who rescue the captives, just as funds to buy the women out of slavery are drying up.

The thousands of Yazidi women and children were taken prisoner in August 2014, when IS fighters overran their villages in northern Iraq with the aim to eliminate the Kurdish-speaking minority because of its ancient faith.

Since then, Arab and Kurdish smugglers managed to free an average of 134 people a month. But by May, an IS crackdown reduced those numbers to just 39 in the last six weeks, according to figures provided by the Kurdistan regional government.

Mirza Danai, founder of the German-Iraqi aid organization Luftbrucke Irak, said in the last two or three months, escape has become more difficult and dangerous.

"They register every slave, every person under their owner, and therefore if she escapes, every Daesh control or checkpoint, or security force - they know that this girl ... has escaped from this owner," he said, using the Arabic acronym for the group.

US State Department spokesman John Kirby told the AP that the US continues "to be appalled by credible reports that Daesh is trafficking in human beings, and sex slavery in particular."

"This depravity not only speaks to the degree to which Daesh cheapens life and repudiates the Islamic faith, it also strengthens our resolve to defeat them," he said.

The AP has obtained a batch of 48 head shots of the captives, smuggled out of the IS-controlled region by an escapee, which people familiar with them say are similar to those in the extremists' slave database and the smartphone apps.

Lamiya Aji Bashar tried to flee four times before finally escaping in March, racing to government-controlled territory with Islamic State group fighters in pursuit. A land mine exploded, killing her companions, 8-year-old Almas and Katherine, 20. She never learned their last names.

The explosion left Lamiya blind in her right eye, her face scarred by melted skin. Saved by the man who smuggled her out, she counts herself among the lucky.

"I managed in the end, thanks to God, I managed to get away from those infidels," the 18-year-told the AP from a bed at her uncle's home in the northern Iraqi town of Baadre. "Even if I had lost both eyes, it would have been worth it, because I have survived them."