A new Islamic State (Isis) video from Syria appears to show a four-year-old British boy blowing up a car with four "spies" inside, killing all of them. The boy in the video has been identified as Isa Dare, the son of London-born Muslim convert Khadija Dare.

In the video three of the victims are interviewed as they sit in the car tied up, "confessing" under duress in Arabic to being British spies. A masked IS (Daesh) militant then appears with the small boy.

Addressing Prime Minister David Cameron, the man says: "You will never fight us except behind fortified fortresses or behind walls...You've only done two things. Firstly, when you sent your spies to Syria and when you authorised for your men, thousands of miles away, to push a button to kill our brothers who lived in the West. So today, we're going to kill your spies the same way they helped you kill our brothers. So prepare your army and gather your nations as we too are preparing our army."

The boy then appears to press a button, detonating explosives which obliterate the car. He then stands beside the charred remains shouting "Allahu Akbar". The men are shown to be dead.

The authenticity of the video has not yet been confirmed, but the boy's mother has posted images of him holding huge guns and her husband was a Swedish militant killed in Syria. Isa's grandfather has also been interviewed and described his horror at his daughter's actions in taking her child to a war zone and parading him on camera.

"They are pure evil for doing this to that little child – pure evil," Isa's granddad told the Mirror. "I burst into tears when I saw it was him."He doesn't like it over there. I spoke to him on the phone and he just said 'Grandad, come and get me'".