Thousands of refugees stuck in the cold in “knee-deep mud” have crossed into Croatia after it gave in and opened its border with Serbia.
“Without any announcement, the borders opened. When the borders opened, everybody rushed,” said UNHCR spokeswoman Melita Sunjic.
“The last person to go was a young boy without a leg, and we helped him cross in a wheelchair.”
Thousands have been stuck in the cold and rain in Serbia for nearly two days, according to the UNHCR – the UN’s refugee agency.
With bad weather hitting the area, some children are said to be suffering from hypothermia as supplies of blankets and rain coats run out.
Play video “Children Suffering On Serbia Border”
Croatia had been restricting the flow of migrants heading north, with Slovenia – the migrants’ next destination – also limiting numbers and creating a backlog.
Aid workers said people fought on Monday and chanted “open the gate” at Croatian police after a night spent lashed by wind and rain.
About 2,000 to 3,000 migrants were at the border when Croatia finally relented, according to the UNHCR.
Croatia’s Prime Minister said he had had a change of heart and that barring the migrants was “no solution”.
“Yesterday we kept 5,000 to 6,000 people [from coming in] on the other side, in Serbia,” said Zoran Milanovic.
“It’s apparent that this is no solution, so we will let them through, we will send them towards Slovenia.”
Mr Milanovic said his country had no plans to build fences, unlike Hungary which has erected metal fences and razor wire to block migrants.
Most people say they are heading north to Germany to claim asylum.
Meanwhile, a train carrying 1,300 migrants has also reached the Croatia-Slovenia border – just hours after another arrived with 1,800 on board.
Tension is building between the two countries.
Slovenia has criticised its neighbour for sending large groups to its border, with its interior minister calling it “completely unacceptable”
Play video “Migration Crisis In Numbers”
The small Alpine country says it can only process 2,500 people each day.
But Croatia itself is struggling with huge numbers – police there say nearly 200,000 have arrived since in the last five weeks.
It became the main route through Europe after Hungary closed its border with Serbia on 15 September.
The EU has agreed a plan, resisted by Hungary and several other ex-Communist members, to share out 120,000 refugees.
This is a small proportion of the 700,000 migrants the International Organisation for Migration (IOM) expects will reach Europe’s borders from the Middle East, Africa and Asia this year.