"In Syria, where militants continue armed attacks on government forces, a November 24 attack on residents of the western part of Aleppo using chemical poisonous substances, presumably chlorine, was a blatant violation of the ceasefire," Putin said, speaking at a BRICS meeting on the sidelines of the G20 summit.
According to Putin, dozens of Syrians were injured, including children.
"Such terrorists' crimes should not left unpunished, otherwise they will replicate such antics," said Putin.
The attack which Putin mentioned occurred on November 24, when terrorist groups located in the Idlib de-escalation zone fired 120-millimeter shells at the north-western districts of Aleppo from the south-eastern part of the demilitarized zone, according to the Russian Defence Ministry's Centre for Syrian Reconciliation.
The shells were filled with poisonous substances, and exploded in the vicinity of Nile Street in the Al-Khalidia neighbourhood.
According to medics, aid had been provided to 73 civilians injured in the attack.
Nusra Front* is a terrorist group banned in Russia