As many as 50 British children, including young babies, are in the clutches of the Islamic State, it emerged last night.

Information from The Times database of 120 former United Kingdom residents who fled to join ISIS revealed that 35 children between the ages of 15 to 18 and more than 60 men between 18 to 30 have joined the Islamic State.

There has been growing concern about the status of children joining ISIS or being taken to war zones; a fear promoted by a newly-released execution video from the Islamic State, in which a masked jihadi threatens the U.K.

At the end of the video, ISIS teases a forthcoming release and features a young boy wearing military clothing, who says, “Go kill the kuffar (non-believer) over there.”

The boy has since been identified by his grandfather as Isa Dare, whose mother Grace fled England for Syria after converting to Islam a couple of years ago.

This comes only days after reports surfaced that the two under-aged Austrian teen girls who were murdered by ISIS were used as sex slaves by Islamic State jihadis.

ISIS has continued its relentless campaign to recruit teenagers and young adults, encouraging them to leave their families and join the caliphate.

In social media posts seen by The Foreign Desk, members of ISIS often share lists of items necessary to “make hijrah” (a term used to describe a holy migration to/for Allah) in their messages, giving teenagers step by step directions on how to make the trip.