Women and girls taken captive and used as sex slaves by Islamic State militants are now having secret abortions and vaginal surgery to avoid being ostracised by their own communities, reports suggest.

According to the Sunday Times, some Kurdish doctors are performing terminations on girls who have been able to escape. Some are even trying to reverse the loss of virginity.

A Yazidi business man who is helping to "re-kidnap" captured girls and take them home told the newspaper that many women feel deeply ashamed about their rape and sexual abuse. "Some girls initially refused to return in the earlier days," Diler Sinjari explained. "They felt ashamed and afraid to come back."

Aid workers reported earlier this month that a nine-year-old girl had become pregnant after being repeatedly raped by at least 10 ISIS militants, and Tearfund's Katie Harrison told Christian Today that girls as young as three have been sold into sex slavery.

A recent Amnesty International report found that there is still a stigma around girls who have been abused by ISIS within the Yazidi community. The group's spiritual leader, Baba Sheikh, urged followers to care for and support those who manage to escape, but Amnesty researchers found that the negative social consequences of being abducted remained a real concern for the families of those concerned.

Some girls said that they couldn't tell their relatives about their abuse for fear of being ostracised, and a number said that they feared it would now be impossible to find suitable husbands.

A minority ethno-religious group, Yazidis have been systematically persecuted by Islamic State during its attempts to create a caliphate. Their religion is an offshoot of Zoroastrianism, which blends ancient religious traditions with both Christianity and Islam. ISIS insurgents believe them to be "devil-worshippers".

Around 3,000 women and girls, the majority of whom are Yazidis, are believed to remain in ISIS captivity, and the UN said last month that militants may have committed genocide against the minority.

A report based on interviews with more than 100 survivors of attacks between June 2014 and February 2015 urged the UN Security Council to refer the issue to the International Criminal Court.

One witness told investigators that ISIS militants laughed as two teenage girls were raped in the next room. A pregnant woman said an Islamic State 'doctor' repeatedly raped her, and sat on her stomach telling her: "this baby should die because it is an infidel; I can make a Muslim baby."

The jihadist group issued guidelines last year, specifying how its followers are to treat their female slaves.

Dated October/November 2014, the Q&A leaflet details exactly how they may buy, sell and abuse "unbelieving" women – thought to mean all those who are not Sunni Muslims.

It clarifies that "It is permissible to have intercourse with the female slave who hasn't reached puberty if she is fit for intercourse," and any female slave who attempts to run away is to be "reprimanded in a way that deters others like her from escaping".

However, Islamic State released more than 200 Yazidi captives on April 8 after taking them captive in Iraq last summer. Some 216 were handed over to Kurdish forces in Himera, north of Baghdad and greeted by family and community leaders. It is not known why they were released.