The evacuation of people from the last opposition-held areas of Aleppo was suspended on Friday after Iran-backed militias demanded that the wounded should also be brought out of two Shia villages under siege by rebel fighters.
A rebel source said "ex-Nusra Front" militants, who are part of the opposition, have yet to agree to the evacuation of wounded from Foua and Kefraya.
The second day of the operation to evacuate Aleppo's rebel enclave ground to a halt amid recriminations from all sides after a morning that had seen the pace of the operation pick up.
On Friday afternoon, a convoy taking evacuees out of the eastern part of Aleppo headed back to the rebel-held enclave.
Earlier a Syrian-regime TV station reported that rebels had breached an agreement with Assad forces by trying to take prisoners with them during the evacuation.
Rebel officials and pro-opposition TV said that Iranian militias had opened fire on and then taken hostage a bus convoy leaving Aleppo.
TRT World's Abubakr Al Shamahi has been following developments from Gaziantep on the Turkish border with Syria.