No civilians were evacuated during the Russian-announced truce in Aleppo, a Red Cross official in the city said after the truce expired at 7 pm Saturday (1600 GMT).
Ingy Sedky, spokeswoman for the International Committee of the Red Cross (ICRC) in Syria, said evacuations were impossible due to the poor security situation in the city.
The Red Cross team was unable to enter rebel-held eastern Aleppo, under siege since July, Sedky said, adding that thee was mortar shelling and sniper fire.
The Russian military announced an 11-hour ceasefire for Thursday to allow civilians, rebel fighters and injured persons to leave the area, promising them safe passage.
It later extended the ceasefire for another two days. Rebels, however, said they would not leave the city.
The Syrian opposition said there were no guarantees that wounded evacuees would not be arrested by government forces and no provision for supplying humanitarian aid to those remaining in the enclave.
Sedky said Friday that ICRC teams were ready to evacuate people but had not received the necessary security guarantees.
The UN Human Rights Council decided Friday to launch an investigation into war crimes against civilians in Aleppo, putting pressure on the Syrian government and its ally Russia, both of whom have been bombarding the rebel-held east.
Some 250,000 to 300,000 civilians are thought to be trapped in eastern Aleppo, with dwindling food supplies and extremely limited medical care in underground hospitals that have themselves been hit repeatedly by airstrikes.