(CNN) Refugees and migrants trying to find their way to a new life in Europe are now facing an added difficulty: increasingly wintry weather in the Balkans.
At the Serbian border crossing of Berkasovo, more than 2,000 people were stuck in "hellish conditions" as they waited to get into Croatia, a U.N. refugee official said Monday.
"We have families, pregnant women, small babies, the elderly, three generations of families, an old woman in a wheel chair. They are in a desperate situation," said Melita Sunjic of the U.N. refugee agency. "The weather is horrible. We need blankets, raincoats, food, they are standing in the mud and their shoes are falling apart. We have cases of hypothermia too."
Restrictions on the flow of migrants -- hundreds of thousands of whom have flocked to Europe so far this year -- have caused bottlenecks throughout the region.
Thousands of migrants caught in European bottleneck
Many people spent Sunday night in "dire conditions" in Trnovec, Croatia, after being prevented from crossing the border into Slovenia, according to Amnesty International.
"Hundreds of children including babies as young as a month old were among the group, who walked or were carried in the rain," the rights group reported.
Amnesty criticized the governments in the region for allowing the crisis to unfold.
"European leaders have known full well for months that a situation like this could arise, but have still failed to prevent it by putting in place available support mechanisms," said Barbora Cernusakova, a researcher for the group at the Croatia-Slovenia border.
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