The total of Syrian refugees abroad stood at 4.6 million at the end of 2015 and rose to 4.85 million by the end of last year.
"As the number of men, women and children fleeing six years of war in Syria passes the five million mark, the international community needs to do more to help them," the UN refugee agency (UNHCR) said in a statement.
The total of Syrian refugees abroad stood at 4.6 million at the end of 2015 and rose to 4.85 million by the end of last year, according to the agency's data.
The first three months of 2017 saw more than 250,000 additional Syrians register as refugees, UNHCR said on its website, without providing an explanation for the apparent surge.
Turkey continues to host the highest number of Syrians displaced by the conflict -- nearly three million.
Lebanon has over a million Syrian refugees, while Jordan has 657,000, with others spread across Iraq, Egypt and other North African countries.
Hundreds of thousands of Syrians have also fled to Europe, but not all of them have been granted refugee status.