Brainwashed youngsters as young as five years old are being turned into executioners by ISIS thugs, a new documentary has revealed.

In a harrowing interview, an 11-year-old refugee, Hadya, revealed he had been forced to hack off a man's limbs with a machete along with his two younger brothers.

'The man came and told us, "You cut off a foot, you cut off an arm, and you stab him in the face with a knife,"' he said.

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Brainwashed youngsters as young as five years old are being turned into executioners by ISIS thugs

'"If you don't, I will take the three of you away from your mother and I will kill you."

'We were scared to say no. He gave each of us a machete. Me, I cut his hand off.'

His brother Fadi, nine, was then forced to cut off the man's foot while his youngest brother Shadi, five, stabbed him in the face and eyes, according to the Mirror.

The man eventually bled to death.

The siblings, who were left traumatised by the ordeal, are currently being held in a refugee camp in northern Iraq.

The interviews were captured as part of a French documentary The Lost Children of the Califate, by filmmaker Sofia Amara.

A 34-minute video called My Father Told Me, shows so-called cubs of the Caliphate in the ISIS stronghold of Raqqa going through military drills in the middle of the night

A child soldier is seen holding a gun in the propaganda video

Another former child soldier, Ayad, was just 12 when he was sent to a military training camp.

As part of training, he said, the children would practice crawling down into tunnels to hide from bombing raids and learned how to place explosives.

He also revealed soldiers whipped them with an electrical cable and shoot next to their feet to make them feel threatened.

'They would tell me how they are going to take over the world, and I would believe that even if I escaped they would find me,' he said.

'So I was forced to become like them.'

The children, who are known as 'cubs of the Califate', are used by the terrorists as suicide bombers and frontline soldiers.

The terrorist group's use of child soldiers is well known, with youngsters appearing in propaganda videos.

Child soldiers are shown going through military drills in the middle of the night

In a 34-minute video, called My Father Told Me, child soldiers in the ISIS stronghold of Raqqa are shown going through military drills in the middle of the night and learning how to use handheld rocket launchers.

Previous videos have shown youngsters shooting jumpsuit-wearing prisoners in the back of the head and delivering chilling threats to the terror group's enemies.

When ISIS seized power in parts of Syria and Iraq in 2013 it took over schools and immediately began 'educating' children the Daesh way.

Staff were ordered to teach their extreme interpretation of the Koran and orphanages were also built, where the orphans came under the protection of ISIS commanders.

With no parents to nurture them or teach them their own morality the orphans could simply be moulded from an early age into brainwashed puppets.