More than 2 million refugees have now fled Syria's civil war, piling pressure on neighbouring host countries, the United Nations said on Tuesday.
The tide of children, women and men crossing borders has risen almost ten-fold over the past 12 months, figures from the U.N. refugee agency UNHCR showed.
"Syria has become the great tragedy of this century - a disgraceful humanitarian calamity with suffering and displacement unparalleled in recent history," the U.N. High Commissioner for Refugees, António Guterres, said in a statement.
On average, almost 5,000 people take refuge in Syria's neighbours every day, according to the report.
"If the situation continues to deteriorate at this rate, the number of refugees will only grow, and some neighbouring countries could be brought to the point of collapse," said UNHCR envoy and Hollywood star Angelina Jolie.
The number of people displaced inside Syria was holding steady at around 4.25 million, the report said.
Ministers from Iraq, Jordan, Lebanon and Turkey - the four main hosts of Syrian refugees - were due to meet officials from the agency in Geneva on Wednesday to work out ways to raise more international aid.
The UNHCR said last month its work had so far stopped the refugee crisis spiralling out of control.
But "a far more substantial and coherent strategy" was needed than the $2.9 billion refugee aid effort already underway it added then.
Syria's uprising against four decades of rule by the family of President Bashar al-Assad has turned into an increasingly sectarian civil war that has killed more than 100,000 people.