The number of Syrian refugees who have fled the conflict has reached one million, the UN has said.
The UN High Commissioner for Refugees said the number of people seeking haven in neighbouring countries had jumped since the beginning of the year.
Half of the refugees were children, the UN said, most under the age of 11 and often traumatised by their experiences.
The largest numbers of refugees were seeking shelter in Jordan, Lebanon, Turkey, Iraq and Egypt.
“Syria is spiralling towards full-scale disaster,” the UNHigh Commissioner for Refugees Antonio Guterres said in a statement, warning that the international humanitarian response capacity was “dangerously stretched”.
“This tragedy has to be stopped,” he added, warning that the influx of people had also stretched the resources of Syria’s neighbours.
Many of those who have fled conflict now live in difficult conditions, with poor sanitation and insufficient resources to cope with the harsh winters.
In Lebanon, for example, the influx of almost a third of a million refugees since last February had swollen the country’s population by 10%.
*. Jordan – 324,543
*. Lebanon – 329,823
*. Turkey – 185,205
*. Iraq – 105,326
*. Egypt – 20,531
*. North Africa – 8,262
Source: UNHCR (based on data from 1-6 March 2013)
Jordan’s desert camp
Voices from Jordan camp Turkey, providing a temporary home for some 184,000 refugees, has spent more than $600m (459m euros; £396m) setting up 17 refugee camps, and was building new ones to meet the increasing need, the UN said.
“These countries should not only be recognised for their unstinting commitment to keeping their borders open for Syrian refugees, they should be massively supported as well,” Mr Guterres said.
On Tuesday, Jordan’s King Abdullah called on world nations to help his country, Turkey and Lebanon to shoulder “the tremendous burden” of caring for the huge influx of people.
The rush of refugees has surprised even UN experts, who had originally estimated that the one million figure would not be reached until the end of June 2013.
In effect, more than 400,000 have became refugees since 1 January 2013.
The UN’s emergency response plan for Syrian refugees, it said, currently lacked 75% of the funding required.
Jordan’s Petra news agency said that a total of 2,257 Syrian refugees had crossed into the country on Tuesday alone.
Some 110,000 of those who have sought shelter in Jordan are living in the desert camp of Zaatari, near its northern border with Syria.
The conflict in Syria began almost two years ago with demonstrations against the government of President Bashar al-Assad.
The protests quickly turned violent as opponents of Mr Assad took up arms to try to resist a brutal crackdown by the authorities.
The conflict has left more than 70,000 people dead and two million internally displaced.