Joe Biden's press secretary Jen Psaki falsely claimed in a long-winded diatribe that biological research facilities in Ukraine are a "conspiracy theory" and "disinformation", despite Biden's State Department confirming their existence just the day before.

"We took note of Russia's false claims about alleged U.S. biological weapons labs and chemical weapons development in Ukraine. We've also seen Chinese officials echo these conspiracy theories," Psaki tweeted Wednesday.

"This is preposterous. It's the kind of disinformation operation we've seen repeatedly from the Russians over the years in Ukraine and in other countries, which have been debunked, and an example of the types of false pretexts we have been warning the Russians would invent."

Psaki went on to say that Russia is about to launch a "false flag operation" with biological weapons to blame on Ukraine, a talking point echoed by the State Department on Tuesday.

"Now that Russia has made these false claims, and China has seemingly endorsed this propaganda, 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. It's a clear pattern," she added.

Psaki's desperate remarks fly in the face of State Department Under Secretary of Political Affairs Victoria Nuland confirming during a Senate Foreign Relations committee hearing that Russia had in fact seized numerous biolabs in Ukraine.