A London grandfather has told ITV News he believes the boy featured in the latest ISIS video is his grandson.
Henry Dare has spoken of his "surprise" and "disappointment" at seeing the boy in the film.
Mr Dare, whose daughter is the known British jihadist Khadjiha Dare, said he had not seen the boy for more than three years, ever since his daughter took him with her to Syria.
Asked if he thought the boy knew what he was doing, Mr Dare told ITV News: "He's a kid, he's a minor. He's under five. He's acting under the influence of the IS leaders."
Video report by ITV News correspondent Rohit Kachroo
In the video the boy, who Mr Dare has identified as his grandson, is seen dressed in military fatigues and wearing a black bandanna.
He speaks with an apparent British accent, saying: "We will kill the kuffar [unbelievers] over there."
Khadijah Dare was born a Christian and grew up in Lewisham, south east London.
But she converted to Islam and became radicalised, moving to Syria in 2012 and marrying Swedish jihadist Abu Bakr in an arranged marriage.
Ms Dare's parents christened her Grace, but she later adopted the name Khadijah.
She is known to have at least two young children and last July posted an image of her son clutching an AK47 on her Twitter account.
The 10-minute video, which shows the killing of five men dressed in orange jumpsuits, also features a masked man who speaks with an apparent British accent.