Russia on Tuesday slammed and dismissed a US warning against the Syrian government for so-called preparations of a fresh chemical attack.

The White House warned on Monday night that Syrian President Bashar al-Assad and his military "will pay a heavy price" if they carry out a chemical weapons attack like the one conducted on April 4. Washington claims that deadly attack was carried out by the Syrian government.

File photo of President Vladimir Putin's spokesman, Dmitry Peskov. /VCG Photo

The White House said they had reason to believe that such preparations were underway.

But Russian President Vladimir Putin's spokesman, Dmitry Peskov, refuted this claim, saying that "such threats to Syria's legitimate leaders are unacceptable."

"I am not aware of any information about a threat that chemical weapons can be used," Peskov told a conference call with reporters.

The Kremlin spokesman also criticized the US for using the phrase of "another chemical weapons attack," arguing that there was no investigation into the April attack, despite Russia's calls for one.

 Destruction at a hospital in Khan Sheikhoun, a rebel-held town in northwest Syria, following the suspected toxic gas attack in April. /VCG Photo

The suspected chemical attack in the rebel-held town of Khan Sheikhoun in April killed over 80 people and hundreds suffered symptoms consistent with a reaction to a nerve agent. 

While the US claimed that the attack was carried out by the Syrian government, President Assad denied the allegation and insisted that the incident was fabricated.

Updated at 9:17 p.m. BJT

Syrian President Bashar al-Assad made a surprise visit to the Russian Hmaymim Airbase in the Latakia Governorate’s Jableh district on Tuesday afternoon, said a CCTV reporter citing a local military source, after the US threats against Syria's so-called preparations of a fresh chemical weapons attack. 

Syrian President Bashar al-Assad visits the Russian Hmaymim Airbase. /SANA Photo

Assad also delivered prayers for Islam's Eid al-Fitr holiday in Hama in west-central Syria on Sunday, and visited the wounded army soldiers.

(Source: Reuters, AP)