NEW details have emerged to suggest that an Austrian teen who fled Europe to join the Islamic State was used as a sex slave for new fighters before she was beaten to death when she tried to escape.

A Tunisian former jihadist who managed to escape from the sick terror group has revealed fresh information about Samra Kesinovic and Sabina Selimovic, IS poster girls who ran away to join the Islamists.

Seventeen-year-old Samra and 15-year-old Sabina disappeared from their homes in 2014, leaving a note for their families which read: “Don’t look for us. We will serve Allah and we will die for him.”

The girls, who are of Bosnian heritage, travelled to Syria via Turkey after allegedly being brainwashed by Bosnian Islamist preacher Ebu Tejma in Vienna.

When they joined up with the terror group, the teenagers were forced to marry IS fighters and were snapped in burqas carrying Kalashnikovs as part of a propaganda drive to recruit more young girls.

MORE: ISIS issues new ruling on sex slaves

But now the Tunisian woman, who was kept in a house with 17-year-old Samra, has revealed they were forced into sexual acts with jihadis.

She said they had lived together in the house and were regarded as a “sexual present for new fighters”.

She claimed Samra had tried to flee several times and after the last attempt she was beaten with a hammer so severely that she died from her injuries.

When the girls fled their homes to join IS last year, 15-year-old Sabina allegedly tweeted: “Here I can really be free. I can practice my religion. I couldn’t do that in Vienna.”

But Sabina was reported dead soon afterwards after being killed during fighting in the jihadi stronghold of Al-Raqqah. Shortly afterwards, Samra penned a letter to her family saying she was so sickened by the Islamic State’s brutality that she wanted to leave, but couldn’t.

Now Austrian media sources say Samra was killed when she tried to leave Al-Raqqah, beaten to death by ISIS thugs.

The Austrian government has yet to confirm the reports and foreign ministry spokesman Thomas Schnoll said: “We cannot comment on individual cases.”

There are thought to be around 190 Austrians in Syria who left Europe to join the terror group.

The revelations come as we learn that Islamic State theologians have issued a new set of rules dictating the ways militants should treat their sex slaves.

The ruling, or fatwa, has the force of law and appears to go beyond the Islamic State’s previous known utterances on slavery. It sheds new light on how the group is trying to reinterpret centuries-old teachings to justify the rape of women.

ISIS fighters laugh about buying female Yazidi slaves In a chilling video, Islamic State militants are seen laughing and talking about buying and selling enslaved Yazidi women and girls - some as young as 15.

The fatwa was among a huge trove of documents captured by US Special Operations Forces during a raid targeting a top Islamic State official in Syria in May.

Among its injunctions are bans on a father and son having sex with the same female slave and the owner of a mother and daughter having sex with both. There are also rules around pregnancy, “joint ownership” and abortions.

ISLAMIC STATE’S NEW RULES

• “It is not permissable for the owner of a female captive to have intercourse with her until after she has her menstrual cycle and becomes clean.”

• “If she is pregnant, he is not allowed to have intercourse with her until after she has given birth.”

• “It is not permissable to cause her to abort if she is pregnant.”

• “If the owner of a female captive releases her, only he can have intercourse with her and he cannot allow someone else to have intercourse with her.”

• “If the owner of a female captive, who has a daughter suitable for intercourse, has sexual relations with the latter, he is not permitted to have intercourse with the mother and she is permanently off-limits to him.”

• “The owner of two sisters is not allowed to have intercourse with both of them.”

• “If the female captive becomes pregnant by her owner, he cannot sell her and she is released after his death.”

• “If two or more individuals are involved in purchasing a female captive, none of them are permitted to have intercourse with her because she is part of a joint ownership.”

The US government’s full translation of the list, which has not been previously published, is here. It makes for grim reading.