India, Oct. 7 -- US Secretary of State Marco Rubio has described the death of a Russian laboratory worker at a plague research centre in Siberia as a "cause for focus" but not alarm, while urging Russia to provide more information about the incident.

"I think it's incumbent upon Russia to obviously share more information with the world," Rubio told reporters, as quoted by the BBC. "We're watching it very closely, hour by hour."

Speaking about the incident, Rubio said, "We know what we know, obviously, about whatever the Russians have provided, which is it seems that there was a worker at the lab that was infected, and there's concern that that could have spread, at least internally."

He added that Russian authorities had imposed quaran...