'I will be the one who slaughters you', says child in IS video

Baghdad, Iraq: A young boy raises a pistol, aims at two kneeling men and fires, in a shocking propaganda video highlighting the Islamic State jihadist group's efforts to indoctrinate another generation with its brutal ideology.

The boy, who doesn't look older than 11 or 12, has allegedly just executed two men said to have confessed to spying for Russia, the voiceover saying their bodies "lay humiliated" at the feet of the young jihadist.

Their fate could not be independently confirmed.

When asked in another video what he wanted to do in the future, the boy said: "I will be the one who slaughters you, O kuffar (unbelievers). I will be a mujahed (holy warrior)."

The video is one of many examples of propaganda aimed at spreading IS's beliefs to a younger generation to aid recruitment and to perpetuate the "caliphate" the group has declared in areas it holds in Iraq and Syria.

Charles Lister, a visiting fellow at the Brookings Doha Center, said that over the past six months IS media materials "have steadily escalated the level of violence involving and being carried out by children, with this video being the most extreme level reached so far".

One of the IS videos shows young boys undergoing classroom instruction in religion and Arabic, then firearms practice and physical training.

The jihadist group makes its aim clear.

"They are the next generation," a narrator says as one camouflage-clad boy quickly assembles a Kalashnikov assault rifle while others look on.

The boy, who calls himself Abdullah and says he is from Kazakhstan, is the same one who "executed" the two alleged spies.

Jeffrey Bates, the spokesman for the UN children's agency UNICEF in Iraq, said ideological indoctrination or participation in violence is incredibly damaging psychologically to the children who undergo it, and poses a major problem for the country.

"We have examples from around the world for decades of the impact this has on children, and it's devastating," Bates said.

"The scope of the problem in Iraq -- you cannot overestimate it. We're looking at... thousands and thousands of children" who will need help.

IS photos said to be from the jihadist stronghold of Raqa in Syria also show young girls wearing Muslim headscarves holding toy assault rifles.