The Islamic State group has released a video purporting to show a young boy executing an Arab Israeli who infiltrated it in Syria to spy for the Jewish state.

In the video, a youth identifying himself as 19-year-old Mohammed Said Ismail Musallam recounts how he was recruited by Israeli intelligence.

Dressed in an orange jumpsuit that is standard in videos of IS executions, he is shown kneeling in front of the boy, who appears to be no more than 12 years old, and a man standing at his side.

The man, speaking in French, issues threats against Jews in France, before the boy walks around in front of the hostage before shooting him in the forehead with a pistol.