India, Oct. 7 -- The death of a lab worker in Russia's Siberia region has sparked concerns over a possible plague case, the UN World Health Organization (WHO) said on Tuesday, adding that it was following the situation closely.

"A woman who worked at the laboratory in Irkutsk oblast has died, and the authorities are looking into whether pneumonic plague caused her death," WHO spokesperson Christian Lindmeier told reporters in Geneva.

He underscored that her workplace was "an institute that studies dangerous pathogens, including plague, in a part of Siberia where plague occurs naturally in wild animals."

Plague is caused by the bacteria Yersinia pestis usually found in small mammals and their fleas.

Pneumonic plague occurs when the bac...