The United Nations says 1.5 million people are in need of aid in Syria, an increase of half a million on its previous estimate.
The UN's office of humanitarian affairs says more and more people are fleeing their homes because of ongoing fighting between anti-regime fighters and government soldiers.
A recent agreement between the UN and the Syrian government on mounting a major aid operation is on hold because of disquiet over security.
Major General Robert Mood suspended patrols by UN monitors in Syria last weekend because of risks to the safety of the 300 observers.
Meanwhile, the bodies of 26 people have been found in the northern province of Allepo.
A human rights group says they are believed to be members of a pro-government militia, but the government says they were civilians killed by armed terrorists.
Video of the bodies has been posted on the internet.