Over 900 civilians were either injured or killed over the past 162 days as a result of the rebels' shelling on government-controlled areas in the northern city of Aleppo, a monitoring group reported on Friday.
The Syrian Observatory for Human Rights said 203 civilians were killed and 700 others injured as a result of the shelling by the so-called Brigade of Badr's Martyrs militant group.
The UK-based group said 42 kids under the age of 18 were among those killed in the shelling that targeted the government-controlled parts of Aleppo city.
The observatory, which relies on a network of activists on ground, said the accused militant group is led by a man named Khaled Hayani, adding that this group used mortar rounds, rockets and explosive-laden gas cylinders in their shelling.
Tens of children and women were among the wounded, said the observatory, adding that 25 percent of the wounded people suffered from permanent disabilities and deformations.
Aleppo, once the economic hub of Syria, has seen the most ferocious battles between the rebels and the government troops.
The rebels have controlled almost half of the city and the majority of its countryside while the government are fighting to dislodge them from the city.