Russian experts conducted the examination on bomb fragments in the northern Syrian city and confirmed the use of toxic weapons by militants there, ministry official Igor Konashenkov said Monday.
More evidence is being collected, Konashenkov added.
He said the Organization for the Prohibition of Chemical Weapons has not yet sent its experts to Aleppo.
Russian warplanes started airstrikes in September 2015 in Syria in support of the Syrian government. In March 2016, Russian President Vladimir Putin ordered to withdraw most of the forces. Enditem