Of the 1.2 million refugees and migrants who applied for asylum in Europe in 2015, nearly 350,000 were children – many of them minors without their parents. Britain has said it will take in some unaccompanied refugee children from Syria, north Africa and other conflict areas, but did not say how many. This is in addition to the 20,000 Syrian refugees the government has pledged to take in by 2020.

Migrants and refugees have had to brave temperatures as low as minus 15 degrees Celsius (5F) to cross frozen Balkan borders en route to western Europe, visibly unprepared for winter and in increasing danger from the cold. Men, women and children covered in blankets have been forced to sleep rough in tents or next to bonfires in the open. Save the Children said that women, children and babies are in danger of contracting hypothermia.

Migrants have been arriving in Serbia with blue lips, distressed and shaking from the cold. Exhausted mothers have told the group's aid workers they are unable to keep their babies warm and dry, and that some have slipped while carrying them on icy roads. The United Nations and aid agencies have warned that children are at risk of freezing to death given their lack of adequate clothing or access to sufficient nutrition.

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A baby girl wrapped in blankets waits with her parents to depart for Croatia at a train station in Presevo, SerbiaMarko Djurica/Reuters
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A family walks through a snowy landscape in sub-zero temperatures near the Macedonian-Serbian borderMilos Bicanski/Getty Images
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A child cries from the cold at a registration camp in Presevo, SerbiaMarko Djurica/Reuters
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A toddler with a bottle sleeps next to other refugees and migrants inside a tent as they wait to cross the Greek-Macedonian borderAlexandros Avramidis/Reuters
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A woman and a child, wrapped in a thermal blanket, wait for a train to Croatia, at a train station in Presevo, SerbiaMarko Djurica/Reuters
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People walk through a frozen field after crossing the border from Macedonia into Serbia, near the village of MiratovacMarko Djurica/Reuters
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Children wait in freezing temperatures near the Macedonian-Serbian borderMilos Bicanski/Getty Images
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Children, sitting on frosty ground, eat soup in a camp near the border between Macedonia and SerbiaMilos Bicanski/Getty Images
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Children wait for hot food in sub-zero temperatures near the Macedonian-Serbian borderMilos Bicanski/Getty Images
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A child carries his belongings as he waits in line with other migrants and refugees for security checks after crossing the Macedonian border into SerbiaArmend Nimani/AFP
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A man carrying his baby walks through a muddy field after crossing into Serbia via the Macedonian borderArmend Nimani/AFP
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A child carrying a loaf of bread holds the hand of a relative after crossing from Macedonia into SerbiaArmend Nimani/AFP
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Mothers push prams through thick mud after crossing into SerbiaMilos Bicanski/Getty Images
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People walk through a field covered in snow after crossing the border from Macedonia into SerbiaMarko Djurica/Reuters
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A Syrian refugee holds her baby next to a bonfire as she waits to cross the Greek-Macedonian borderAlexandros Avramidis/Reuters
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Syrian refugees rest next to a highway near the village of Thourio in northeastern GreeceAlexandros Avramidis/Reuters
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A baby sits on the ground as migrants and refugees wait for a bus at a transit camp in the southern Serbian town of PresevoArmend Nimani/AFP
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A man carries a child at the Grande-Synthe camp, near Dunkirk, where some 2,500 migrants and refugees live, mostly Iraqi Kurds and SyriansPhilippe Huguen/AFP
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A woman comforts her sleeping child while waiting at a station for a train in the southern Serbian town of PresevoDimitar Dilkoff/AFP
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A boy waits for a train to leave the town of Presevo in southern SerbiaArmend Nimani/AFP
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An Afghan migrant child poses while waiting at a reception centre to receive Serbian papers which will allow them to take a trainMilos Bicanski/Getty Images
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A child waits to receive papers that will allow travel to the Macedonian-Serbian borderMilos Bicanski/Getty Images
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A girl poses with her coat on her head as she waits for a security check after crossing the Macedonian border into SerbiaArmend Nimani/AFP
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Families walk along a snow-covered road near the Macedonian-Serbian borderMilos Bicanski/Getty Images
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A boy is covered with a blanket as he and other refugees and migrants wait to cross the Greek-Macedonian borderAlexandros Avramidis/Reuters
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A man carrying a child waits in line for a security check near the village of Miratovac in SerbiaArmend Nimani/AFP
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A Syrian refugee child wearing a lifejacket is pictured moments after arriving on a raft on a beach on the Greek island of LesbosGiorgos Moutafis/Reuters
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A child runs in a muddy field at a camp of makeshift shelters for migrants and asylum-seekers from Iraq, Kurdistan, Iran and Syria, called the Grande Synthe jungle, near Dunkirk, FranceYves Herman/Reuters
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Migrants and refugees sleep covered with blankets as they wait to cross the border from Greece into MacedoniaAlexandros Avramidis/Reuters

Many of the people making this arduous journey are fleeing conflict zones such as Syria, Iraq and Yemen, where millions of people are gripped by hunger, struggling to survive with little help from the outside world. Children suffer from severe malnutrition, their parents often having to beg or sell possessions to get basic commodities including water, medicine and fuel. According to the UN children's agency, malnutrition is a major threat for millions of refugees.