United Nations High Commissioner for Refugees spokesman Adrian Edwards said in a release that 253,106 Syrians have sought refuge from the violence in their country.
The agency said there are 85,197 refugees in Jordan, 66,915 in Lebanon, 22,563 in Iraq and 78,431 in Turkey.
The report came as Antonio Gutteres, U.N. high commissioner for refugees, and actress and agency special envoy Angelina Jolie, toured the Za'atri refugee camp in Jordan, holding 28,000 refugees near the Syrian border, to draw attention to the needs of the swelling population.
"I am grateful to Jordan and the other border countries for keeping their borders open, for saving these people's lives. They are dying in Syria," Jolie said.
Speaking in Geneva, Switzerland, Edwards said the visit by Gutteres and Jolie was aimed at showing solidarity with refugees and recognizing Jordan's commitment to the protection of vulnerable citizens.
Within Syria, the World Health Organization said a United Nations mission to the city of Homs found the city's largest hospital destroyed and 500,000 people in need of aid, including food, water and healthcare.
At least half the doctors in the city of 2 million have left, and only three surgeons remain, said Tarik Jasarevic, World Health Organization spokesman.
The Syrian Network for Human Rights documented the deaths of 54 people Tuesday, identified by name, city and cause of death, the majority having been "killed in random shelling" or "killed by army gunfire" after their names.