The White House said late on Monday the preparations in Syria were similar to actions before an April 4 chemical attack which killed dozens of civilians and prompted U.S. President Donald Trump to order a missile strike on a Syrian air base.
But Russia challenged the U.S. intelligence.
"I am not aware of any information about a threat that chemical weapons can be used," Kremlin spokesman Dmitry Peskov told a conference call with reporters on Tuesday.
"Certainly, we consider such threats to the legitimate leadership of the Syrian Arab Republic unacceptable."
Russian officials have privately described the war in Syria as the biggest source of tension between Moscow and Washington, and the cruise missile strike ordered by Trump in April raised the risk of confrontation between them.
The Syrian military and foreign ministry did not immediately comment on the White House statement though a Syrian state-run television station, al-Ikhbariya, said the White House's allegations were fabricated.
White House officials did not respond to requests for comment on the intelligence that prompted the statement, or on possible U.S. plans if Syria carried out such an attack.
"If ... Mr. Assad conducts another mass murder attack using chemical weapons, he and his military will pay a heavy price," White House spokesman Sean Spicer said.
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27 June 2017 - 15:27
News ID: 839118
(AhlulBayt News Agency) - Russia denounced a U.S. warning that the Syrian leadership will pay a heavy price for any chemical weapons attack, and dismissed White House assertions that a strike was being prepared as "unacceptable".
