The Islamic State (Isis) terrorists in Iraq have issued a fatwa calling for the killing of newborn babies born with Down's Syndrome or congenital deformities in Mosul, a local activist has revealed.

According to the details posted on Mosul Eye Facebook page, the Isis terrorists till now have killed 38 babies in total since it issued the fatwa. Mosul Eye is the pseudonym of a local historian who secretly has been documenting Isis atrocities in Mosul since the militants overran the city in June 2014.

"Through monitoring and following the death incidents of children with Down's Syndrome and congenital deformities, we were able to learn that the Sharia Board of [Isis/Daesh] issued an 'Oral Fatwa' to its members authorising them to kill newborn babies with Down's Syndrome, congenital deformities and disabled children," Mosul Eye said.

The fatwa was issued by a Daesh Sharia judge from Saudi Arabia identified as Abu Said Al Jazrawi. The media activist revealed that at least 38 newborn babies aged one week to three months have been executed by the Sunni radical group.

"They were killed by either lethal injection or suffocation," Mosul Eye revealed. While the veracity of the claim could not be verified independently, the radical members who are part of Isis have in the past committed several such heinous crimes.

Since taking over swathes of land in Syria and Iraq, the Sunni radical group has gone on to impose its own version of Sharia law. Under its archaic punishments stoning, beheading, crucifixion and rape are part of the daily lives of the local residents.

A report in July revealed shocking depraved behaviour by the Sunni group, when Isis soldiers booby-trapped a baby and blew it up during a training session in Iraq's Salahuddin.

In another instance, Daesh fighters shot at a pregnant woman and her husband -- who were rushing to the hospital as the woman was in labour -- for breaking the night curfew in the Syrian city of Raqqa.