Syria activists say Aleppo air raids killed 100

Civilians continue to pay the highest price in the conflict after even the most modest attempts at peace have failed.

On Monday alone, at least 150 people were killed nation-wide, according to the Observatory, which relies on a wide network of activists on the ground.

Most of the casualties were reported in and around Syria's largest cities, including in the capital, Damascus, Aleppo and the central city of Homs.

The high daily death toll coincided with the United Nations' $6.5 billion appeal to help displaced Syrians and their host countries as civil war is expected to rage on well into 2014.

Nearly 9 million Syrians have been uprooted from their homes, with some 2.3 million fleeing into neighboring countries and millions of other searching for shelter in safer parts of Syria.