An aid convoy planned to bring assistance to besieged civilians in Syria's rebel enclave of Eastern Ghouta will not go through, the International Committee of the Red Cross said.
"The convoy is postponed as the situation is evolving on the ground, which doesn't allow us to carry out the operation in such conditions," ICRC spokeswoman Ingy Sedky said.
The joint convoy of the ICRC, United Nations and Syrian Arab Red Crescent had been expected to deliver aid to Eastern Ghouta's main town of Douma.
It marks the second time this week that desperately needed aid operations to Eastern Ghouta have been disrupted by military developments.
On Monday, 46 trucks of assistance entered the area in the first aid provision since a new offensive against the enclave began on February 18 - but they had to cut their deliveries short and leave due to heavy bombardment by Russian and Syrian forces.
Nearly half of the food aid could not be delivered while the UN said Syrian authorities removed some medical and health supplies from the trucks. Eastern Ghouta has been besieged since 2013, making food, medicine, and other daily goods exceedingly difficult to access.
Aid deliveries into the area require permission from all warring sides.