The group, in a statement released by the High Commissioner for Refugees, called on the Syrian government and rebel groups to stop targeting civilians.
"As reports are piling up of indiscriminate shelling of civilians, enforced disappearances and executions, another horror of the war in Syria is becoming apparent: the deprivation of basic necessities of life and the denial of humanitarian relief as a method of war," they warned.
The U.N. says about 6.5 million Syrians are internal refugees. It estimates 6 million people in the country are in critical need of food and 9.3 million need some form of assistance.
Notable deaths of 2014 [PHOTOS]