"The provocations are continuing that spawn such insinuations and unfounded accusations against the Syrian leadership," Kremlin spokesman Dmitry Peskov told journalists.
He commented after the UN Human Rights Council on Monday ordered investigators to examine the latest violence in Syria.
The Council condemned "the indiscriminate use of heavy weapons and aerial bombardments against civilians, and the alleged use of chemical weapons in Eastern Ghouta".
"In Syria the chemical weapons were destroyed. That was verified not only by the Russian side but by the OPCW (Organisation for the Prohibition of Chemical Weapons)," Peskov insisted.
Damascus and its key ally Moscow face growing pressure after reports last month of suspected chlorine use in the battered rebel-held enclave of Eastern Ghouta, where Syria's army is carrying out a ground and air assault.
The Britain-based Syrian Observatory for Human Rights said a child suffocated to death and 13 other people fell ill from a suspected chlorine attack in the Eastern Ghouta region on February 25.
A doctor who treated those affected told AFP that he suspected chemical weapons, most likely a chlorine gas attack, with a three-year-old dying of asphyxiation.
Russian Foreign Minister Sergei Lavrov immediately responded that the reports were "bogus".
Peskov said Tuesday that for Russia, such accusations need to be based on "the findings of an international commission, an international working group, only the result of an impartial investigation."
Syrians receive medical treatment after Assad regime's alleged chemical gas attack over oppositions' frontline in July 2017. Source: Getty
"In the absence of such an investigation, all accusations are nothing but insinuations," he said.
The Syrian government has denied possessing chemical weapons and said that it considers their use unacceptable.
So far the bombardment by Syrian regime forces on Eastern Ghouta has killed more than 700 civilians, the Syrian Observatory says.
UN chief Antonio Guterres has said the region's 400,000 residents "live in hell on Earth".
