At least 45,000 people have fled fighting in Syria's southwestern Deraa province, heading towards the border with Jordan, the United Nations said on Tuesday.

Jens Laerke, spokesman of the U.N. Office for the Coordination of Humanitarian Affairs (OCHA), said that civilians including children had been killed and injured and a hospital had been put out of operation by an air strike.

Bettina Luescher, spokeswoman of the U.N.'s World Food Programme (WFP), told the ssame briefing: "We expect the number of displaced people could nearly double as violence escalates."