Islamic State (IS) is paying smugglers' fees for child refugees in an attempt to attract new recruits to the extremist group, says an influential think tank.

Refuge: Pathways of Youth Fleeing Extremism, a report by counter-terrorist think tank Quilliam, estimates 88,300 children identified by Europol as missing are at risk of being radicalised.

"Young unaccompanied refugees are more vulnerable to radicalisation if they are separated from their parents, who remained in the country of origin at risk to violent and radical groups, or in a new host country," said the report. "There is no question that militant groups target refugee youth for recruitment."

Quilliam investigated the ways in which extremist groups recruit fighters, reports The Guardian. The think tank found that IS and Boko Haram, among other groups, had been using mainly financial incentives, as well as food, to target refugees, rather than ideological or religious indoctrination.

Militant groups offered up to $2,000 (£1,600) to recruit fighters from within refugee camps in Lebanon and Jordan, added the think-tank. In 2016, Jordanian special forces uncovered what they called an "IS sleeper cell" in a refugee camp near Irbid in northern Jordan.

Researchers identified the four places where refugees were at the highest risk of being radicalised: their home country, their first point of refuge, and the sea routes into Europe and south-east Asia.

Quilliam's report, published today, criticised the approach of European countries – particularly the UK – towards protecting solo child refugees.

Senior researcher Nikita Malik said: "Young asylum seekers are targeted by extremist groups as they are more vulnerable to indoctrination, make able fighters and, in the case of girls, can create a new generation of recruits. This report outlines national and international requirements to reduce the risk of child-trafficking, extremism and modern slavery."

Hundreds of refugee children sleeping rough in -10C sheets

24 January

Nearly 2,000 refugees, including up to 300 children, are sleeping rough in freezing conditions on the streets of Belgrade, says Save The Children.

It is estimated that children make up almost half of the 100 refugees and migrants pouring into Serbia every day and that one in five underage refugees are travelling alone. Children as young as eight were found among 1,000 people taking shelter in an abandoned warehouse behind a train station in the capital.

Underage refugees and migrants attempting to cross into Hungary and Croatia are regularly forced back into Serbia, sometimes violently, by police in those bordering countries, the charity claims.

"The group estimated that 1,600 such cases - 30 incidents per day - have taken place in the past two months," Time magazine reports.

In response to plummeting temperatures, Serbian authorities have opened emergency shelters, catering to around 2,000 migrants and refugees.

However, Tatjana Ristic, from Save the Children, says the makeshift accommodation offers scant protection and the charity is calling on the EU to increase funding for shelters.

"Conditions are truly gruesome. These buildings don't have heating, windows, toilets; they don't have water," she told The Independent.

Adding in those sleeping rough or squatting, "this could be the biggest unofficial refugee camp in Europe", she said.

Serbia has become a popular destination for people hoping to enter neighbouring Hungary, Bulgaria and Romania.

A deal struck between the EU and Turkey last year has stemmed the flow of migrants arriving by water, but has led to an increase in the numbers trying to enter Europe on foot through the Balkans.

Parts of Europe have experienced extremely cold temperatures this winter, with more than 60 deaths from hypothermia, illness and accidents connected to the weather, making the overland route a perilous prospect.

Earlier this month, villagers in a Bulgarian mountain town on the border with Turkey came across the bodies of two Iraqi migrant men who had frozen to death while braving blizzards to cross into the country.