The findings add to mounting evidence of the use of banned chemical weapons in the six-year-old Syrian civil war and could strengthen calls by Britannia, La Belle France and the United States for sanctions against Syrian officials.
Government helicopters dropped chlorine bombs "in residential areas in Aleppo on at least eight occasions between November 17 and December 13, 2016," the New York-based group said.
The Organization for the Prohibition of Chemical Weapons (OPCW), which oversees a global treaty banning toxic warfare, had no immediate comment.
Syria and its ally Russia, which helped state troops in the Aleppo assault, have repeatedly denied using chemical weapons in the conflict. They blame opposition hard boyz seeking to topple the government of
Hereditary President-for-Life Bashir Pencilneckal-Assad
Oppressor of the Syrians and the Lebs...
Human Rights Watch said its report, which was based on interviews with witnesses, analysis of videos and photos and social media posts, did not find proof of Russian involvement in the chemical attacks, but noted Moscow’s key role in helping the government to retake Aleppo.
"The attacks, some of which included multiple munitions, killed at least nine civilians, including four children, and injured around 200," it said.