More than 650,000 people have fled the conflict in Syria, a top United Nations official said on Wednesday, as Turkey's foreign minister pledged Ankara would continue to accept refugees.
Speaking at the World Economic Forum in Davos, UN aid chief Valerie Amos said the humanitarian situation in Syria was "already catastrophic and clearly getting worse".
"The harsh winter is exacerbating the already appalling conditions. More than 650,000 people have left the country," she added.
The United Nations says more than 60,000 people have died in the Syria conflict which began 22 months ago with peaceful protests that erupted into deadly violence in the wake of a harsh regime crackdown.
The UN has also predicted that the number of Syrian refugees in neighbouring countries will double to 1.1 million by June if the civil war does not end.
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"I hope there is no doubt left in the mind of our political leaders as to the scale of the human tragedy unfolding in Syria," said Amos.
Turkish Foreign Minister Ahmet Davutoglu said his country was sheltering some 160,000 refugees in 16 camps and announced that his government was building another to house the steady flow of people fleeing the unrest.
"We will continue to have a policy of open door and we will never close our borders," pledged Davutoglu, although he acknowledged: "The flow of refugees is really alarming us."
"We don't know how many children we lost. We don't know how many pregnant women we lost who also lost their children," he said.
"How long will we wait? How long will the Security Council be silent in front of this humanitarian crisis."