ISIS terrorists in Syria
ISIS terrorists in Syria Reuters

The Islamic State (ISIS) jihadist group burned 19 Yazidi girls alive after they refused to have sex with its fighters, according to reports.

The girls were locked in cages before being publicly executed in the city of Mosul in northern Iraq, according to the Kurdish ARA news agency.

The gruesome spectacle took place in front of hundreds of people, according to local media activist Abdullah al-Malla.

"They were punished for refusing to have sex with ISIS militants," he told ARA.

Mosul is ISIS's de-facto capital in Iraq, and the country's second largest city.

ISIS views the Yazidis - members of an ancient religion who are of Kurdish ethnicity- as heretics and "fire-worshipers," drawing on long-held misconceptions and prejudices against the Yazidis by many Muslims.

When ISIS overran northern Iraq it engaged in a systematic genocide of the Yazidi population, murdering the men and taking the women and children captive, forcing many into sex slavery.

US and Iran-backed Iraqi and Kurdish forces are rumored to have plans to take Mosul, but for now Iraqi forces are focusing on recapturing Fallujah, the other major city held by the jihadists in that country, while Kurdish fighters say they are not prepared to take the Arab-majority city alone.