MOSCOW - Russia warned against "false" information as reports emerged of a second suspected case of plague in Siberia, with Washington and Brussels calling for transparency and neighbouring Mongolia tightening health surveillance.
Russian news outlet People of Baikal reported last Friday that a 28-year-old woman employed at a plague research institute in Siberia's Irkutsk region had died of the disease, possibly after contracting it from a broken test tube.
International concern has meanwhile grown over the death and suspicions that a second employee at the institute fell ill.
The United States, the European Union and the World Health Organization have all called on Russia to be transparent about the situation.
Mongolia's government said Wednesday that "health surveillance and monitoring measures (were) being implemented at the border" with Russia.
WHO chief Tedros Adhanom Ghebreyesus also urged Moscow to clarify "media reports of a second employee with pneumonia of undetermined cause" at the Irkutsk institute.
Russian authorities have played down the reports, determining the woman died of pneumonia and insisting there was no risk of an outbreak.
Asked about reports of a second case, Kremlin spokesman Dmitry Peskov told reporters that "the vast majority of what the media is reporting regarding this situation is false information".
People should rely solely on official statements from Russian health watchdog Rospotrebnadzor, he insisted.
US President Donald Trump, asked if a "bio-weapon" was involved, told reporters in the Oval Office: "We don't think so. We're going to find out soon enough, but we don't think so."
"If you listen to them, it's under control. But you know, people have said that before about other things," he added.
The Russian health agency said earlier on Wednesday that it had determined "there are no epidemic risks for the population".
It said extensive investigations had uncovered "no emergencies" and that the lab had complied with "proper control when working with pathogenic microorganisms".
"More than 90 percent of contacts have completed medical observation," it added.
"No health disorders associated with infectious pathology were detected," it said, adding that "the results of almost 5,000 laboratory tests did not reveal any dangerous pathogenic microorganisms".
The agency also said the woman had been "vaccinated and had immunity to dangerous infections with which she worked".