“The Kremlin is intentionally spreading outright lies that the US and Ukraine are conducting chemical and biological weapons activities in Ukraine,” State Department spokesman Ned Price said in a statement.

“Russia is inventing false pretexts in an attempt to justify its own horrific actions in Ukraine.”

White House Press Secretary Jen Psaki said the claims were “preposterous” and noted that “we’ve also seen Chinese officials echo these conspiracy theories”.

“Now that Russia has made these false claims … we should all be on the lookout for Russia to possibly use chemical or biological weapons in Ukraine, or to create a false flag operation using them,” she said on Twitter.

On March 6, Moscow’s foreign ministry tweeted that Russian forces found evidence that Kyiv was erasing traces of the military-biological programme in Ukraine, allegedly financed by the US.

Price said “this Russian disinformation is total nonsense” and added that Russia had “a track record of accusing the West of the very crimes that Russia itself is perpetrating”.

The US said Tuesday however it was working with Ukraine to prevent invading Russian forces from seizing biological research material in the country.