ISIS, the militant group wreaking havoc across Iraq and Syria, has ordered all women and girls in and around Iraq's northern city of Mosul to undergo female genital mutilation, according to a United Nations report.

Update: The report's claim is disputed, as experts have expressed skepticism on the edict from the Islamic State the UN found.

If the document is indeed a hoax, then the UN isn't the only one fooled. UK Secretary of State for International Development Justine Greening has also tweeted the document.

In the document, the Sunni Muslim fighters say they're issuing a "fatwa" that could affect about 4 million women and girls, according to U.N. resident and humanitarian coordinator in Iraq Jacqueline Badcock, who told reporters:

This is something very new for Iraq, particularly in this area, and is of grave concern and does need to be addressed... This is not the will of Iraqi people, or the women of Iraq in these vulnerable areas covered by the terrorists.

ISIS has been taking over northern and western Iraq, rapidly capturing towns in its offensive against the Shiite-led government in Baghdad. ISIS leader Abu Bakr al-Baghdadi has said this latest order is to "distance [women and girls] from debauchery and immorality."

Some African, Middle Eastern, and Asian communities practice the ritual procedure of removing external genitalia or internal female organs, despite its negative impact on girls and women. According to the World Health Organization, FGM "has no health benefits" and "causes severe pain and has several immediate and long-term health consequences, including difficulties in childbirth also causing dangers to the child."

The WHO also states that more than 125 million girls and women alive today have undergone the procedure in the 29 countries. In 2008, the World Health Assembly passed a resolution pushing for the elimination of FGM, and in 2012, the UN General Assembly approved a resolution calling for all member states to ban the practice.