The last U.N. estimate in July put the death toll from the 3-year-old Syrian civil war at 100,000, though activists more recently gave a figure of 120,000.
Along with 6.5 million internally displaced people, there are 2.3 million Syrians who have fled the country during the war.
Most of those are scattered in refugee camps and informal settlements across Lebanon, Jordan and Turkey.
On Monday, the U.N. and other aid groups said they would need $6.5 billion to help the displaced Syrians in 2014, the largest-ever appeal for a single crisis.