On Wednesday morning the Syrian Red Crescent had said 100 trucks carrying flour, other food supplies and medicines were preparing to leave for five besieged areas.
The UN announced on Tuesday night that deliveries would be made to seven besieged areas, as UN envoy Staffan de Mistura held talks in Damascus aimed at restoring hope for a cessation of hostilities that world powers want in place by Friday.
About 40 trucks were headed for Moadimayet al-Sham, a rebel-held town near Damascus encircled by Syrian forces, Muhannad al-Asadi of the Red Crescent told AFP.
Another 35 vehicles were to travel to Madaya and Zabadani, two other regime-besieged towns near Damascus, and 29 were to go to Fuaa and Kafraya, two Shiite towns in northwestern Idlib province besieged by rebels, he said.
Almost half a million people in Syria are in areas under siege, according to the UN, France 24 reported.