Documents 'obtained from Isis offices' reveal strict guidelines on extremist ideology

The materials spell out beard requirements and guidelines for taking women as sex slaves

Members of the Iraqi forces said the documents originated from Isis (Zohra Bensemra/Reuters)

Documents and posters obtained from villages held by Isis have revealed a strict system of rule by the militants, spelling out required beard lengths and guidelines for taking women as sex slaves.

Colourful posters and pamphlets, found in offices that were being used by Isis just days before, reportedly bear the group's logo and go to great lengths to explain their extremist ideology.

Members of the Iraqi forces told Reuters the documents originated from Isis, although this could not be independently verified.

One of the pamphlets reportedly states: ''Wearing beards is compulsory, shaving is prohibited'' before defining that a beard is “hair that grows on your face and your cheeks.”

Another green wallet-size insert lays out guidelines for how to pray properly, showing an image of a young boy undertaking ablutions and reading: “Wash your feet from the direction of your toes down to your heels,” according to Reuters.

A pink and red pamphlet is said to include 32 questions and answers on how to deal with female captives, including a rule stating senior Isis clerics may distribute female captives among its fighters.

The leaflet reportedly reads: "Non-Muslim women can be taken as concubines," before adding that militants can own two sisters as concubines but only have sex with one.

It is also said to state that underage women and girls can be sexually exploited, stating: "Pre-pubescent girls can be taken as concubines. You cannot have penetrative sex but you can still enjoy them.”

When establishing its caliphate Isis took hundreds of women from the Yazidi minority as sex slaves and abused them on a daily basis.

Under Isis's rules women are required to stay at home or wear head-to-toe black coverings if they went out. Men meanwhile wear shorts that were deemed Islamic along with beards of appropriate shape and length.

Iraqi security forces and Kurdish peshmerga fighters have so far seized several villages and towns during an offensive against the northern city of Mosul, Isis's last stronghold in the country.

Isis is trying to move up to 25,000 people into Mosul as they prepare for what is likely to be an intense battle for control of the city now that Iraqi coalition forces have reached its outskirts.

The offensive to liberate Mosul - home to some 1.5 million people - is likely to be long and gruelling, with fighting expected to go from house-to-house and street-to-street.