23/08/2014 08:20 BST | Updated 23/08/2014 08:59 BST

The Islamic State's Latest Recruit Is A 13-Year-Old Belgian Schoolboy, Leading Academic Warns

Twitter/ AP

Posing with an AK-47 and with deep-set bags under his eyes, this baby-faced schoolboy is believed to be one of the Islamic State's youngest jihadists, aged just 13.

This troubling picture is said to show a young Belgian boy who left his country to become one of the many foreign fighters waging jihad in Syria.

Leading academic Shiraz Maher, a senior fellow at King’s College London’s International Centre for the Study of Radicalisation and Political Violence, posted the chilling image of the boy, who he named as Younes Abaaound.

Mr Maher said the boy travelled from Belgium with his brother Abdelhamid Abaaoud, 27, earlier this year and is believed be among dozens of child-fighters in the war zone recruited from Europe.

Posting the image on Twitter - one of several of Younes to surface online in weeks - Mr Maher wrote: "One of the youngest foreign fighters we know of Younes Abaaoud, who was 13 when he left Belgium to join ISIS."

Younes’s father, reportedly a shopkeeper called Omar and originally from Morocco, has said the boy was taken to Syria after Abdelhamid had been brainwashed in Belgium.

Media reports in Belgium are not clear if the boy is fighting, or living away from the front lines.

It is estimated up to 200 Belgian citizens have left the country to fight in Syria. Britain has among the highest number of extremists fighting for IS - at least 500 - but Belgium contributes more jihadists per head to the conflict than any other European country. Europe's authorities are struggling to stem the flow.

For Europeans, travelling to Syria is a cheap flight to Turkey and a quick trip over the border, "so the problem is one faced by many countries", Reuters reported in March.

Several recent reports have already claimed to show children fighting for the terrorist group.

The chilling image of Abaaound follows a horrific picture which was posted online by convicted Australian terrorist Khaled Sharrouf, showing his seven-year-old son holding a decapitated head in Syria.

The image was posted with the caption: “That’s my boy.”

'That's my boy': This horrific picture was reportedly posted to Khaled Sharrouf's twitter account


Met Police Give You Another Reason Not To Watch Islamic State Beheading Video

People Are Seriously Outraged About The New York Post's Front Page

US Attempted And Failed To Rescue American Hostages In Syria

Shock And Fury As Video Shows Beheading Of US Journalist

British IS Militants 'Among Most Vicious'

This Is The Way We Should Remember James Foley

Killing Is Just The Latest Beheading By Extremists

The United Nations have voiced their condemnation, stating that the IS are responsible for recruiting children.

“Armed opposition groups have been responsible for the recruitment and use of children both in combat and support roles, as well as for conducting military operations, including using terror tactics, in civilian-populated areas, leading to civilian casualties, including children,” a United Nations report on children in Syria, published last February stated.

The Islamic State militants have gathered such a strong backing from foreigners taking part in "terrorist tourism" who do not speak Arabic that some units have reportedly had to employ translators to ensure orders are understood.

A documentary by Vice found one Islamic State unit in Syria that had to have interpreters who could speak Russian, English, French and Dutch.

In the harrowing film, young men with British accents echo the disturbing rhetoric expressed by Lee Rigby's killer Michael Adebolajo and declare jihad against the UK and United States.

The world was left horrified this week after a jihadist with an English accent brutally executed the American journalist James Foley.

Footage issued by Islamic State militants that shows 'jihad John'

10 Things We Know About James Foley's Left-Handed 'British' Killer

The jihadist in the execution video, which shows Foley kneeling in the desert with his head shaved and wearing an orange jumpsuit before he is beheaded, is believed to be the ringleader of a group of UK-born extremists, and using the name 'John'.

They are apparently responsible for guarding Western hostages in the stronghold of Raqqa, and nicknamed after members of the Beatles, with the two others dubbed Paul and Ringo.