Dozens of people have been killed in a day-long battle between Syrian rebels and government forces in western Aleppo, the Syrian Observatory for Human Rights and combatant sources on both sides said.
The combatant sources gave conflicting accounts of the outcome of the battle that began early on Tuesday (local time) in and around the Jamiyat al-Zahraa area of western Aleppo.
A rebel said insurgents had managed to take some ground from the government side, while the army said the attack was repelled.
The fighting threatened the army's defensive lines around government-held areas of western Aleppo.
Observatory director Rami Abdulrahman said dozens had been killed on both sides in what he described as the most intense battle in the area in a year. Government forces were reinforced by allies from Lebanon's Hezbollah, he said.
The rebel fighter said about 40 government fighters had been killed, while rebel losses stood at 10 dead.
The military source denied heavy casualties in army ranks, but said dozens of civilians and many rebels had been killed.
The rebel and a second opposition fighter said insurgents had at one point captured a strategic location known as Family House, but later lost it after the government side brought in reinforcements.