Kremlin spokesman Dmitry Peskov said he had no information about such a threat from the Syrian regime.
“I think that my counterparts from the intelligence services and the Defence Ministry would share their anxiety if such information emerges,” Peskov said in comments carried by state news agency TASS.
He alleged that terrorist groups in the war-torn, Middle Eastern country have perpetrated numerous chemical attacks and could again in the future.
Russia is the main military backer of Syrian President Bashar al-Assad in the country’s multisided civil war.
The US supports some rebel groups seeking to depose al-Assad and leads a military coalition against the UN-designated terrorist group Islamic State.
The US said Monday it had identified “potential preparations” by the Syrian government for a chemical weapons attack similar to the one in April on the rebel-held town of Khan Sheikhoun in Syria’s north-western Idlib province.
The White House warned that al-Assad would pay a “heavy price” if such an attack went ahead.
Earlier this year the US conducted a cruise missile assault on a Syrian airbase that it claimed was responsible for April’s chemical attack.