Syrian government forces and Islamic State jihadists carried out new chemical attacks in and around Aleppo in August and September, the New York-based Human Rights Watch said in a statement on Wednesday.
The watchdog said that two neighbourhoods in rebel-held eastern Aleppo, al-Sukari on September 6 and Zabdiya on August 10, were hit with Syrian regime barrel bombs containing toxic chemicals. Five people, including three children, were killed and dozens were injured, it added.
"After each attack, dozens of people suffering from a shortage of breath, coughing, reddened skin and eyes, and excessive tearing sought medical treatment in hospitals," HRW said.
According to HRW, identifying the chemical allegedly used in the Aleppo attacks without laboratory testing is difficult, "but the signs and symptoms reported by victims and medical personnel indicate that government forces probably used chlorine."
The alleged chemical attack by Islamic State (or ISIS) happened away from the besieged city.
"On August 16, several large, locally made mortar shells struck Marea, a town 30 kilometres north of Aleppo controlled by the armed opposition group the Free Syrian Army and near the front line with ISIS forces," HRW reported, citing video interviews of residents conducted by a local journalist.
A first responder and medical professional said that up to 10 people close to the impact site suffered from symptoms leading them to believe that the mortar rounds contained chemicals, the HRW statement said.
The Chemical Weapons Convention prohibits the use of the toxic properties of common chemicals such as chlorine to kill or injure.