Russia urged to share more information on plague lab worker's death

US Secretary of State Marco Rubio has urged Russia to release more information about the death of a lab worker at a plague research centre in Siberia.



The incident has sparked a flurry of speculation about the circumstances in which the 28-year-old woman died.



Russian officials have said they are still investigating the cause of the death but those who came into contact with the victim all tested negative to pneumonic plague.



Reports first emerged on Friday of almost 200 people being placed under observation in Siberia's Irkutsk region following the death.



The lab worker, named in Russian media as Darya Shipilova, had reportedly fallen ill a couple of days earlier.



Unconfirmed reports suggested that she had become ill after breaking a test tube containing the pathogen or following a field trip to a region where plague occurs naturally among wild rodents.