The workshop was discovered in a recently-liberated area in Eastern Ghouta where Syrian troops are fighting foreign-backed extremists and Takfiri terrorists, Russian news agencies reported Monday, citing a field commander.
The US and its western and regional allies have often pointed their fingers at the Syrian government for chemical attacks, which Damascus has consistently denied.
Syria surrendered its chemical stockpiles in 2014 under the supervision of the UN and the Organization for the Prohibition of Chemical Weapons.
The discovery of the workshop is yet another revelation in a prolonged debate on who used chemical weapons in Syria.
Back in 2012, a video was released showing the terrorists testing a chemical substance on lab rabbits and threatening to use it against pro-government Syrians.