Images published by an anti-ISIS activist in Syria show a man kneeling in a red jumpsuit while a young boy points a handgun at his head.

It is not clear if he in fact pulls the trigger to kill the prisoner, but another photograph shows the captive lying facing down in the dirt as the child stands over him.

The photographs are just the latest in a long series of sick execution videos ISIS has released in which it claims its child soldiers - named the 'Cubs of the Caliphate' - have carried out killings.

It was suggested on social media the man was killed for spying in Al Jazeera - a likely reference to the Arabian Peninsula, rather than the news broadcaster.

However, many of ISIS's claims must be viewed with a dose of skepticism. Known for its sophisticated propaganda machine, evidence of camera trickery has led many to believe some of the organisation's videos have been staged.

However, its use of child soldiers is not doubted, with young boys are indoctrinated into ISIS's extremist views from an early age.

Given weapons and encouraged to kill, its legions of child soldiers are sent off to military 'training camps'.

There they are made to run, climb and crawl through treacherous assault courses near the terror group's adopted capital of Raqqa, Syria, while an adult commander supervises them.

Armed with rocket launchers and AK47s, the so-called 'Cubs' then pose proudly under its notorious black flag.

ISIS boasts about the training academies through its social media channels and heralds them as 'martyrs' when they die in suicide attacks - which they are brainwashed into believing are a 'great honour'.

Early last month ISIS released an execution video from inside Palmyra, showing 25 child executioners lining up regime soldiers in a Roman amphitheatre and shooting them in the head.

A baying crowd of men and boys gathered in the restored ruin waiting for the slaughter, many wearing military uniforms and headscarves.

The amphitheatre had formerly been used for an annual festival in the city and was a world famous tourist attraction before the Syrian Civil War broke out in 2011.

Just weeks later footage of the group's notorious Speicher massacre, in Tikrit, Iraq, emerged.

Among the dozens of shootings broadcast in the 22 minute-long film was footage of a young boy grasping a handgun with both hands on the banks of the River Tigris.

There he shot at least two prisoners dead after they were dragged before him by masked adults.

(dailymail.co.uk)