The official who declined to be identified in order to speak freely indicated however that the next phase of the Aleppo campaign could be more difficult as the army and its allies seek to capture more densely populated areas of the city.
The rebels have lost more than a third of the area they held in eastern Aleppo in the last few days of a government assault that has killed hundreds of people and uprooted thousands more. For the rebels, it is one of the gravest moments of the war.
Rebels meanwhile fought fiercely to stop government forces advancing deeper into the opposition-held enclave on Tuesday, confronting pro-Assad militias who sought to move into the area from the southeast, a rebel official said.