The UN High Commissioner for Refugees Antonio Guterres said on Sunday there could be two or three times the one million registered Syrian refugees outside the country by the end of 2013 if the rise in numbers continues at its current rate.
The one millionth Syrian refugee was registered in Jordan on Wednesday, following a dramatic acceleration in the number of civilians fleeing fighting in their homeland in the first two months of this year.
Syrians started trickling out of the country nearly two years ago when President Bashar al-Assad's forces shot at pro-democracy protests inspired by Arab revolts elsewhere.
The uprising has since turned into an increasingly sectarian struggle between armed rebels and government soldiers and militias. An estimated 70,000 people have been killed.
The UN refugee body, UNHCR, says more than 400,000 Syrian refugees – nearly half the total – have fled Syria since Jan. 1.
Around half the refugees are children, most of them under 11.
In December, there were 3,000 refugees on average a day. In January, it had risen to 5,000. By February, there were 8,000.
"If this escalation goes on ... we might have in the end of the year a much larger number of refugees, two or three times the present level," Guterres told reporters in Ankara.
Most refugees have fled to Lebanon, Jordan, Turkey, Iraq and Egypt and some to North Africa and Europe. In addition to the refugees, the UNHCR says more than two million of Syria's 22 million people have been internally displaced.