Disarmament of syria
US to fight Islamic State in Syria 'as long as they want to fight': Mattis
Russia, which has a long-term military garrison in Syria, has said it wants foreign forces to quit the country eventually.
Amnesty said the executions took place between 2011 and 2015, but were probably still being carried out and amounted to war crimes.
The insurgents, facing fierce bombardment and ground attacks, had withdrawn from the northern part of eastern Aleppo.
State media cited an Aleppo hospital director saying three dozen people had suffered suffocation.
The assault was mainly focused on the city’s western edge by rebels based in the countryside outside Aleppo.
Rescue workers said that Syria’s military backed by Russian warplanes had killed more than 150 people.
Among at least 25 injured, eight were in critical condition and taken to Turkish hospitals across the border.
The Syrian government launched an assault to capture rebel-held areas of Aleppo last month with Russian.
Putin had been due to meet French President Francois Hollande and open a new Orthodox church next week.
The operation has also targeted a Kurdish militia whose presence along its border Turkey sees as a threat.
The offer of amnesty follows two weeks of the heaviest bombardment of the five-and-a-half-year civil war.
The army said it was reducing its air strikes to alleviate the humanitarian situation.
The Syrian army told the insurgents to leave their positions, offering safe passage and aid supplies.
The Syrian Observatory for Human Rights said government forces had built on the Handarat advance.
The Syrian military announced the major new offensive against the area on Thursday night.
The assault on Aleppo could be the biggest battle yet in a civil war that has killed over 400,000 people.
Video images filmed by residents showed a young girl screaming as rescuers frantically dug her out of rubble.
An impassioned Kerry faced off with Russian Foreign Minister Sergei Lavrov at the UN Security Council.
An impassioned Kerry faced off with Russian Foreign Minister Sergei Lavrov at the UN Security Council.