"The cold is making life increasingly miserable" at the Zaatari camp in Jordan, UNICEF said last week. It cited health problems such as diarrhea and dehydration, a lack of hot water for bathing and a need for winter clothes, blankets and better food.

More than 540,000 Syrians have fled to Jordan, Iraq, Lebanon, Turkey and Egypt, the United Nations said. About half the refugees are children.