“We see this as an attempt to divert attention to some kind of ephemeral, allegedly existing threat against the backdrop of a scandal that is flaring up in the world involving chemical and biological weapons programmes that the US has been carrying out in various countries, including Ukraine,” Kremlin spokesman Dmitry Peskov said.

“There are many people in the world who are worried about what the Americans were doing, what we still don’t know and what could have happened because of all this research and what could potentially happen in the future,” he said.

The Russian defence ministry this week accused Biden’s son, Hunter Biden, of funding biological weapons labs in Ukraine through his investment fund Rosemont Seneca.

“Of course we will demand explanations,” Peskov said today.

“And not only us,” he said, adding that China also had questions.

On Monday, the US president said it was “clear” Russia was considering using chemical and biological weapons in Ukraine and warned of a “severe” western response if it chose to do so.

He also denied that the US was holding chemical and biological weapons in Europe.

“Simply not true. I guarantee you,” he told a gathering of US business leaders in Washington.