Isis is providing young boys and girls in the territory it controls with apps to access violent jihadi websites, as it makes increasing use of child fighters in a battle for survival in Iraq and Syria.

The attempt to “create a new generation of terrorists”, say military and security officials, comes amid evidence of a new drive to recruit among the young in the West to carry out attacks in Europe and America as well as make the journey to the Middle East to join the fighting.

There has been a sharp rise in the numbers of children on the frontline – up to 50,000 according to some estimates – in the wake of the heavy losses Isis has suffered while desperately defending Mosul, its last stronghold in Iraq, and Raqqa, the capital of its “caliphate” in Syria.

Around 300 young fighters have been killed, many in suicide attacks, and others too are likely to die as the campaign continues. Isis is, however, believed to have more than 1,500 in its “Cubs of the Caliphate” section, and security officials warn of a serious problem over what to do with indoctrinated boys and girls, psychologically damaged by what they have experienced, once the conflict is finally over.

The internet is the common avenue for indoctrination in both the West and the Middle-East for the young, say security sources. The British Government has disclosed that 50 young people were prevented from leaving the UK to go to Syria in the last 12 months – more than doubling last year’s figure of 23 at a time when the number of adults making the journey has dropped.

A dozen suspects, all teenagers, are reported to have been detained in Belgium last week for allegedly plotting to attack Christmas shoppers and a 12-year-old-boy was arrested in the German town of Ldwigshafen earlier this month after attempting to detonate a nail bomb at a Christmas market.

Isis has set up kiosks in the areas it controls in Iraq and Syria where children can use apps to read the Isis online magazine Rumiyah, as well as a website that teaches them Arabic.

Rumiyah has replaced Dabiq, another publication produced by Isis, in a move which has been interpreted as reflecting its changing strategy and aims. The town of Dabiq in northern Syria is, in Islamic scriptures, the setting for the final battle in which Muslims will defeat infidels. But in retreat, and losing tranches of land, the jihadis no longer see themselves as being victorious in a war in the Middle-East, and want to take jihad to the heart, as they see it, of political and spiritual power of the West : Rumiyah, or Rome.

Pictures of guns and tanks abound in the childrens’ Arabic learning website along with those of landmarks in Europe and America. Colonel John Dorrian, of the US-led coalition against Isis, said “what they do is despicable, they are willing to use children to carry out suicide attacks: their apocalyptic vision is of damaging society everywhere they have gained control. What they are trying to do is create a generational problem with their poisonous ideology.”

In pictures: Isis' weapons factories Show all 11 1 /11 In pictures: Isis' weapons factories In pictures: Isis' weapons factories A mortar round fin manufactured by Isis in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis rocket components discovered in Gogjali, Mosul, Iraq in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortars discovered near Karamlais, Iraq, in November 2016 CAR In pictures: Isis' weapons factories An Isis rocket launch frame in Qaraqosh, November 2016 Conflict Armament Research In pictures: Isis' weapons factories A memo from Isis' COSQC on quality control at a manufacturing facility in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Electrically-operated initiators manufactured by Isis in forces Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortar tubes at a manufacturing facility in Karamlais, November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis mortar production facility discovered in Gogjali, Mosul, in November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis weapons manufacturing facilities near Mosul in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Stocks of French-manufactured Sorbitol, Latvian potassium nitrate and Lebanese sugar at an Isis weapons factory in Iraq Conflict Armament Research In pictures: Isis' weapons factories A destroyed Isis weapons facility in Qaraqosh, Iraq, November 2016 Conflict Armament Research

“They have even devised an app which is used to indoctrinate children. It is supposed to teach them Arabic. But the words they learn are related to violence and extremism such as tanks and grenades. The children are rewarded if they say they are prepared to carry out attacks on the West, the targets are places like the Statue of Liberty, Big Ben and the Eiffel Tower.

“We are obviously very concerned about what they are learning through these apps turning to reality. But at the same time we need to take care of these children when the time comes, untold damage has been done to them which needs to be undone.”

The vast majority of children in the ranks of Isis are Syrian and Iraqi, with large numbers of Yemenis and Moroccans among those from elsewhere in the region. There are also around 50 from Britain, along with smaller numbers from France, Australia and other Western countries.