Americans urge Russia to release more info about plague lab death

US President Donald Trump says he has arranged a call with his Russian counterpart Vladimir Putin to discuss the case of a possible pneumonic plague at a Siberia research institute.

US Secretary of State Marco Rubio also prompts Russian authorities to release more information on the incident which Washington is watching closely.

A spokesperson for the World Health Organization says Russia, which is required under global health rules to promptly respond to requests, tells the United Nations agency that it records no cases of plague in Irkutsk City after the death of a lab technician last week.

A full range of preventive measures - including tracing of the victim's contacts, medical monitoring and lab tests - were carried out.

A Russian health official says no presence of dangerous infectious disease pathogens was found in any of the contacts.

An investigation is still ongoing amid a flurry of speculation about the circumstances in which the young woman died.

Russia's health watchdog has downplayed the incident and says she was killed by "pneumonia of an unknown etiology."

WHO, which claims the case presents a "very low" risk outside Russia, says on Wednesday it requested more information on the cause of her death, emphasising transparency is vital to get a clear picture of potential health risks.

Donald Trump has signalled willingness to help Moscow with the situation.

Talking to reporters at the White House on Tuesday, the US president confirms he'll be speaking with Putin very soon.

(Reporter: Mr. President, on the plague in Russia, have you spoken with President Putin?)

Trump says: "I have a call scheduled, yep."

(Reporter: When is that call scheduled for?)

Trump says: "Very soon."

(Reporter: What are the intelligence agencies saying about the Russian plague?)

Trump says: "So far, we're in very deep discussions. We'll be able to report about it probably tomorrow."

Speaking during his trip to Iceland, US Secretary of State Marco Rubio says Washington is watching the situation "very closely, hour-by-hour" and adds they have measures available if the situation turns out to be more serious than claimed.

"I think it's incumbent upon Russia to obviously share more information with the world, that's what they should do. That's what we hope they will do," Rubio says. "And the more we can learn about what happened, then the better all of us can be in a position of responding."