Washington DC - President Donald Trump on Tuesday said he will soon speak with Russian President Vladimir Putin about the reported plague death of a laboratory technician in Siberia.

Washington is showing growing concern over a suspected plague outbreak in Russia, despite repeated denials by Moscow. Secretary of State Marco Rubio has called for transparency about the situation, as has the World Health Organization.

"We encourage Russia to be transparent and share more information with the world so that all of us could react accordingly and appropriately," Rubio said during a trip to Iceland.

Trump later said he would be speaking to Putin about what happened, confirming to reporters at the White House that, "I have a call scheduled, yes," and it will happen "very soon."

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Asked what US intelligence agencies were saying about the situation, Trump added: "We're in very deep discussions. We'll be able to report on it probably tomorrow."

The Wall Street Journal reported that the State Department had sent Russia a confidential diplomatic communication, known as a demarche, warning Moscow that failure to disclose details runs counter to its international health obligations.

Russian news outlet People of Baikal reported Friday that the woman who died may have contracted pneumonic plague from a broken test tube. Other media reported a possible link between her death and a lab accident at the facility.

The World Health Organization (WHO) said that an update received Tuesday from Russia stressed that "no case of this dangerous disease has been recorded in the city of Irkutsk."

But its director Tedros Adhanom Ghebreyesus later urged Moscow to be transparent, saying the WHO had "requested further information" on the cause of the pneumonia case and other details.

"Timely, complete and transparent information sharing under the International Health Regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks," he wrote on X.