The woman who died, whose first name was given by Russian media as Daria and who was in her late twenties, had recently visited the Buryatia region on the border with Mongolia.

The plague bacterium or Yersinia pestis, external, which killed up to half the population of Europe in the 14th Century when it was known as the Black Death, is found among rodents such as marmots in the area.

It was in response to an outbreak in the 1920s that the Anti-Plague Institute of Siberia and the Far East, external was founded just over 100 years ago.

Dr Simon Clarke, an associate professor in cellular microbiology at the University of Reading, told BBC Radio 4's PM programme that the pneumonic version of Yersinia pestis was nearly always fatal if left untreated, but could be overcome with antibiotics.

"Pneumonic plague can transmit from person to person and that is why there is the concern around this," he said.

He added: "But of course people's thought with any outbreak of infectious disease at all runs to... lockdowns and Covid and that is just not what's going to happen here."

"People think, 'Oh the plague, that's gone, that went hundreds of years ago,' but it hasn't," Clarke said.

"It's still around and in certain parts of the world, it's a threat to human health and that's why they need to study it."

Asked if the pathogen might have been studied for potential use as a bio-weapon, the scientist agreed it was possible.

"Because this is Russia people's thoughts are running to that, but I think my earlier explanation is probably more likely," Clarke said.