The number of people fleeing the conflict in Syria has escalated to an average of 6,000 a day during 2013, according to UN High Commissioner for Refugees Antonio Guterres.
"We have not seen a refugee outflow escalate at such a frightening rate since the Rwandan genocide almost 20 years ago," Guterres on Tuesday told a rare public briefing to the UN Security Council on Syria, where a government crackdown on pro-democracy protests more than two years ago has spiralled into civil war.
Guterres said that two-thirds of the nearly 1.8m refugees registered with the United Nations in Lebanon, Turkey, Jordan, Iraq, Egypt and elsewhere had left Syria since the beginning of the year.
Ivan Simonovic, UN Assistant Secretary-General for Human Rights told the Security Council that between March 2011 and the end of April 2013 at least 92,901 people were killed in Syria of which more than 6,500 were children.
"The extremely high rate of killings nowadays - approximately 5,000 a month - demonstrates the drastic deterioration of the conflict," Simonovic told the council meeting.
The Security Council has been deadlocked on Syria.
Russia, an ally of Syrian President Bashar al-Assad, and China have three times blocked action against Assad that was backed by the remaining veto powers - the US, Britain and France.
Al Jazeera's diplomatic editor, James Bays, reporting from the UN in New York said that the UN representatives pointed out that there are restrictions set by the Syrian government in getting aid to people.
"Only 14 international aid organisations are allowed in," he said.
Syria's UN Ambassador Bashar Ja'afari said the Syrian government was doing "everything possible to shoulder its responsibility and its duty to its people, to meet the humanitarian needs and the basic needs of its citizens."
UN aid chief Valerie Amos said the world was "not only watching the destruction of a country but also of its people".
She said 6.8m Syrians need urgent humanitarian assistance, including more than 4.2m internally displaced, and that almost half of those needing help were children.
The latest assessment by the World Food Programme was that four million people can no longer meet their basic food needs.