Russian Foreign Ministry spokeswoman Maria Zakharova said on Thursday that Moscow has received information that Syrian rebels have already fabricated video material to accuse Damascus of a chemical attack.
She did not elaborate.
The White House has said Assad is preparing for another chemical attack and warmed that the Syrian ruler will "pay a heavy price" if he unleashes it.
The US in April struck a Syrian air base, which it said had been used to stage a deadly chemical attack. Russia argued that the victims had died of exposure to toxic agents released when Syrian warplanes hit a rebels' chemical weapons depot.
Disclaimer: No Business Standard Journalist was involved in creation of this content