One of the boys carrying out the executions is claimed to be from the UK
The Islamic State has released a new video appearing to show five children killing Kurdish prisoners.
The footage allegedly taken in Syria shows the five boys, one of whom is identified as a Briton, shooting five kneeling men in orange jumpsuits.
The identity of the boy, who is white and appears to be about 11 years old, has not been verified.
The children are all of a similar age and appear in the video wearing military fatigues, black hats and gloves.
In the footage, one of the boys addresses the captives, who are described as "atheist Kurds", and pledges more violence.
Children have repeatedly featured in IS propaganda.
In February, the militant group released a video showing a young British boy wearing an IS bandana and a camouflage outfit.
That child, thought to be aged under five, was the son of Grace 'Khadija' Dare - a Muslim convert extremist from Lewisham in southeast London.
Dare travelled to Syria in 2012.