Indonesian children have been filmed carrying out a mock execution in the name of Islamic State, with the would-be boy gunman proclaiming "I will kill them one by one".

The chilling 18-second clip was uploaded to social media overnight with the tag line: "A message for Jokowi and Obama" in reference to Indonesian President Joko Widodo and US President Barack Obama.

It is believed, however, that the video was created before the start of the year. It shows a group of 10 children crammed into a small room.

Delivering a message to the world leaders, the child 'executioner' stands in the middle of the screen, dwarfed by his fatigues and with a balaclava obscuring his face.


Two children, also in army fatigues and balaclavas, stand behind him holding an Islamic State banner.

Meanwhile, seven boys in different coloured T-shirts kneel before him with their heads bowed.

Waving what looks to be an imitation black handgun, the boy yells "To Jokowi and Obama, these are your soldiers. I will kill them one by one so that the whole world knows that these are for you.

"Allahu Akbar (God is great). Takbir. Allahu Akbar," he says.

The boy then systematically walks along the line of children who are kneeling in front of him and pretends to shoot each of them in the back of the head.

The children fall forward and lie on their bellies before pretending to writhe in agony as the boy returns along the line to deliver each another fake bullet.

No one but the lead boy says anything throughout the video.

It comes a week after seven ISIS supporters were sentenced in Jakarta over their support of the terrorist group and more than a month after the deadly attack in the capital.

Terrorism experts have warned the bombings and shootings in the city on January 14 were likely to be the sign of more violence to come as three men - Bahrumsyah, Bahrun Naim and Abu Jandal - and various pro-ISIS groups try to gain supremacy within Indonesia.

Indonesia, the world's most populous Muslim nation, has long wrestled with the problem of extremism.

About 800 of its citizens have travelled to the Middle East to join radical groups including Islamic State, also known as ISIS, of which about 50 had been killed.

In November, Indonesia's Co-ordinating Minister for Political, Legal and Security, Luhut Panjaitan, said authorities in the archipelago were also monitoring about 100 people who had already returned from the battlefields in Iraq and Syria.