Sex slavery and human trafficking has been a typical method of raising revenue for ISIS.

"They cut off men’s heads and kidnapped girls and women and took them to ISIS stronghold Raqqa.

What were the slaves guilty of? This is a sin," one woman said.

And a man said: "They forced women to be fully covered and never show any part of the body."However they made their slaves strip in order to sell them.

"If someone was caught on the streets during prayer, she would be given 100 lashes."

ISIS target women under the age of 40 to sell as sex slaves, reports say, Daily Stars reports.

A price list verified as authentic by the UN confirms the fact that younger women are preferred by the terror group.

The list showed women aged 40 and over were priced at $41 (£27).

Horrific Video Show ISIS Trading in “Slaves Market”

Horrific Video Show ISIS Trading in “Slaves Market”

A Canadian businessman Steve Maman told Russia Today he is doing all he can to return the victims to safety.He negotiates the women's release by reasoning with the captors or refunding them the amount of money they paid at the twisted sex slave market.

Mr Maman said: "We are not funding ISIS or the captors, we are refunding them."

Many businessmen and rich people in Iraq try this method to free captured girls and women. Most of ISIS sex slavery victims is Yazidis’ women and children.

ISIS are even forcing women not sold as sex slaves to cover their faces if they have beautiful eyes.

The feared all-female Al Khansa brigade – ISIS police force who deal with women – has ordered girls to wear double veils so their eyes remain hidden.