Damascus "utterly rejects" a recent Human Rights Watch report that said its military and allied forces had used chemical weapons during their capture of Aleppo last year, Syrian state media reported on Wednesday.

"An official source at the Foreign Ministry confirmed that the government... utterly rejects the false allegations," Syria's official SANA news agency reported.

Human Rights Watch, which monitors abuses around the world, said in the report published on Monday that Syrian government forces had dropped chlorine bombs "in residential areas in Aleppo on at least eight occasions" late last year.

Syria and its ally Russia, which helped the government's troops in the assault on Aleppo, have repeatedly denied using chemical weapons in the conflict and have instead accused rebels of deploying poison gas.

Syria's civil war pits President Bashar al-Assad, backed by Russia, Iran and Shi'ite militias against rebel groups including some supported by the United States, Turkey and Gulf monarchies, as well as Islamist militant factions.

The army's capture of Aleppo in late December after months of siege and an intense bombardment gave Assad his biggest victory in the war so far, but involved an air and artillery bombardment that caused destruction across whole districts.