Syria's government on Wednesday fiercely denied accusations by Human Rights Watch that it used chemical weapons in its battle for Aleppo, shrugging off the group's report as "unprofessional and unscientific". 

In a major report released Monday, Human Rights Watch said Syrian government forces had carried out at least eight chemical attacks in late 2016 as they were fighting to capture second city Aleppo.

But a Syrian foreign ministry source cited by state media said the report was based on fabricated testimony. 

"The government of the Syrian Arab Republic altogether denies the false allegations made in Human Rights Watch's report," the source said.

"Human Rights Watch's reliance on terrorist media sources and on fake eyewitnesses... proves this report's lack of credibility," it said, describing the conclusions as "unprofessional and unscientific". 

HRW said it interviewed witnesses, collected photos and reviewed video footage indicating that chlorine bombs were dropped from government helicopters during the offensive from November 17 to December 13.

It concluded that nine people, including four children, were killed and another 200 were injured by the toxic gases used on opposition-controlled areas of the northern city. 

Syria's government regained full control of Aleppo in late December, in the biggest win for President Bashar al-Assad's regime since the conflict first began in March 2011. 

Chlorine use as a weapon is banned under the Chemical Weapons Convention, which Syria joined in 2013 under pressure from Russia.

A joint investigation by the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) found that several units of the Syrian army had used toxic weapons against three villages in northern Syria in 2014 and 2015.

And in January, the United States announced new sanctions against 18 senior Syrian miliary officers and officials over the use of chemical weapons. 

Source: AFP