The UN said on Friday it was considering a different route to send desperately needed aid to east Aleppo, to circumvent the blocked main supply route as new air raids pounded Syria's second city.
"We are trying to see by all means available how we can reach east Aleppo," Jens Laerke, spokesman for the UN humanitarian agency United Nations Office for the Coordination of Humanitarian Affairs (OCHA), told reporters in Geneva.
He said the lack of access to the estimated 250,000 residents of rebel-held east Aleppo amid renewed air strikes and fighting was "tragic."
The UN had hoped to send aid from Turkey and along the key Castello Road into east Aleppo, militarily encircled since early July.
As part of the now broken ceasefire pact agreed between the US and Russia, the UN had expected assurances that the Castello Road would be clear and safe.
But those assurances have not come, and the Syrian army has announced a new offensive aimed at retaking all of the divided second city, with Syrian and Russian aircraft pounding the area on Friday.
"What has been happening in Aleppo is not a situation where you can confidently say, yes we can confidently drive a humanitarian aid convoy into that carnage," Laerke said, describing the situation as "grim."
The UN resumed deliveries on Thursday after a pause in the wake of a strike on a humanitarian aid convoy in Syria's north that killed 20 civilians and destroyed 18 aid trucks.
Route via Damascus?
Laerke explained that the UN was now considering sending aid along a much longer route through Damascus, but that when such a convoy could move would depend on the security situation on the ground.
"That is still being planned for. When that will happen, frankly that is out of our hands," he said.
In the meantime, 40 trucks are still sitting at the Turkish-Syrian border waiting to move if the situation improves.
The United Nations humanitarian taskforce for Syria, Jan Egeland, told reporters Thursday that the food in those trucks would go bad within days, but Laerke said that statement was incorrect.
"The food in those 40 trucks is fit for consumption for several months," he said.
Laerke said that a convoy of 23 trucks had successfully delivered aid, including medical supplies, for 35,000 people to the besieged Damascus suburb of Moadamiyat al-Sham.
The conflict in Syria has cost more than 300,000 lives since 2011, and forced more than half the population to flee their homes.