Yazidi refugee Islamic State Isis rape survivor
Ilham (pictured), a Yazidi woman, was kidnapped by Islamic State in August 2014. She was raped several times by one of the extremists. When she tried to escape, some people she asked for help handed her back to the militants. (Asmaa Waguih/Reuters)

Islamic State (Isis) has released a five-page document claiming that "forced sex" is not rape, but is an Islamic practice which is inspired by the Prophet Mohammed.

The document also brands Michelle Obama as a prostitute whose "price won't exceed a third of a dinar".

These horrific remarks were made by a jihadi bride, Umm Sumayyah Al-Muhajirah, in the ninth edition of its propaganda magazine Dabiq, in a feature entitled: "Slave girls or prostitutes".

In a previous edition of Dabiq, Al-Muhajirah calls for other Muslim women – her "sisters" – to immigrate to Syria and become wives to IS extremists.

In the latest article, she claims that keeping enemy prisoners of war and civilians as slaves during war is justified in the "great prophetic Sunnah (teachings of Mohamed) containing many divine wisdoms and religious benefits" in Islamic traditions.

For years IS has been enslaving and sexually abusing the women it captures – particularly from Iraq's minority Yazidi community – and sending the "prettiest virgins" to depraved auctions, a United Nations envoy claimed this week.

The terror group justifies the horrendous sex crimes as Sunnah – a way of life prescribed by Mohammed's life and the Quran's teachings.

While the Quran does detail rules for the ownership and ethical treatment of slaves, it also advises slave owners to free slaved people, even if this required buying them first.

Islamic scholars have estimated Muhammad and his family released nearly 40,000 slaves.

First Lady is worth "third of a dīnār"

In her five-page-document the extremist writer insults Michelle Obama saying that "who knows, maybe Michelle Obama's price won't even exceed a third of a dīnār, and a third of a dīnār is too much for her!"

The fanatical writer admits that IS has looted villages and kidnapped women, saying: "As for the slave-girl that was taken by the swords of men following the cheerful warrior then her enslavement is in opposition to human rights and copulation with her is rape?! What is wrong with you? How do you make such a judgment? What is your religion? What is your law? Rather, tell me who is your lord?' Allah has opened the lands for His awliya [supporter], so they entered and dispersed within the lands, killing the fighters of the kuffar [non-believer], capturing their women, and enslaving their children."

A UN envoy who interviewed dozens of sexual abuse victims in the region said earlier this month that Isis is using widespread and systematically sexual violence as a "terrorist" tactic to spread fear.

IS has carried out 'systematic sexual crimes' against Yazidi women and girls, having captured hundreds of them from northern Iraq over the last two years, Human Rights Watch has said.

In early April, more than 200 Yazidi women, children and elderly were released near Kirkuk after being taken hostage by Islamic State extremists last June.