Observers from the human rights organization spent 10 days in Aleppo earlier this month, documenting 30 attacks that killed more than 80 civilians. Most of the victims were killed by government forces who used indiscriminate air strikes and artillery attacks to target neighbourhoods where opposition rebels had a foothold, it said.
The Amnesty report describes one air attack on Aug. 6 that killed 10 members of one family, including seven children, in two neighbouring houses. Schools and hospitals have also been attacked. Many have also died while waiting for bread in long lines outside bakeries.
Amnesty said government forces have also attacked neighbourhoods where no opposition fighters were present. They talked to one man whose home came under withering artillery fire in the early morning hours of Aug. 8. Amnesty observers found a shell fragment caught in a mosquito net covering the cot where a baby had been killed. The bed where her two-year-old brother had been sleeping was covered in blood.
"Why are we being bombed in our own homes," the father asked. "My baby daughter is gone, my boy and my wife may not survive, my mother who was in great health was killed. Why such attacks? There are no fighters here."
The laws of war
Fighting a war in a dense urban environment poses obvious risks for civilians. So the laws of war require all sides to take steps to minimize civilian casualties. Amnesty says the widespread use by Syrian government forces of battlefield weapons that "have a wide impact radius and/or wide margin of error" like artillery shells, mortars and free-fall unguided bombs and rockets have led to large numbers of civilian deaths and injuries.
"The continued use of such weapons in civilian areas, in full knowledge of the fact that they have and will continue to inflict heavy civilian casualties...is a flagrant violation of the prohibition of indiscriminate attack."
Amnesty International said it was also investigating reports of civilians being tortured or summarily executed. A relative told Amnesty about one raid where a teacher and his two sons, aged 18 and 20, were targeted.
"When the men stormed the apartment, the family know that they were likely to be officers from the Air Force Intelligence, as they are the main security force operating in the area," he said. "[20-year-old] Mahmud was on the internet. Like many kids his age, he had been making anti-government remarks on Facebook and the like. The men examined the laptop and took it....then they left, taking the two boys and their father and the family car."
Their bodies were found the next day, dumped in the family car.
Another man who saw three male relatives summarily executed by members of a shahiba militia working with government forces (he was wounded and left for dead) said remarks from their captors suggested the four were targeted in an act of revenge because they were from a village that supported the opposition.
Amnesty says the bodies of young men, most of the time handcuffed, bearing marks of torture, and shot in the head, are found every few days near the headquarters of Air Force Intelligence, which is in a government-controlled area.
The Amnesty report says government forces were behind the "overwhelming majority" of attacks that led to civilian casualties and it repeatedly accuses pro-government forces of violating international humanitarian law.
But opposition fighters also come in for criticism. Amnesty's report notes that opposition fighters have at times used "inherently indiscriminate weapons" like mortars and home-made rockets that pose a danger to civilians.
It also outlines abuses and unlawful killings by armed opposition groups.
"Amnesty International is alarmed that a pattern of extrajudicial and summary executions by all parties in the conflict appears to be gathering pace."
Rebel groups seeking to oust President Bashar al-Assad have been clashing with government forces in several parts of Syria.
Human rights groups say more than 19,000 people have died since the fighting began last year. More than 13,000 of those deaths are among civilians.