The World Health Organization (WHO) recommended that Ukrainian public health labs that handle infectious agents destroy any "high-threat pathogens" to prevent potential spills during the ongoing Russian invasion, the agency told Reuters on Thursday (March 10).

The WHO previously worked with Ukrainian public health labs to establish security protocols aimed at preventing the "accidental or deliberate" release of such pathogens, the agency told Reuters in an email. "As part of this work, the WHO has strongly recommended to the Ministry of Health in Ukraine and other responsible bodies to destroy high-threat pathogens to prevent any potential spills," the email read.

The agency also advised all affected parties "to reach out for technical assistance as needed," regarding the safe and secure disposal of any pathogens.

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The WHO did not specify when this recommendation was issued, whether the recommendation had been acted upon yet, or which specific pathogens would need to be destroyed, Reuters reported. Ukrainian officials in Kyiv and the embassy in Washington, D.C., did not respond to Reuters' requests for comment.

Public health labs in Ukraine and elsewhere work with pathogens and toxins in order to understand their inner workings; their impact on humans and animals; their modes of transmission, if relevant; and the ways in which their damaging effects might be countered with medical treatments. Ukraine's labs are supported by the U.S., European Union and the WHO, according to Reuters.

The WHO email made no mention of pathogens that could potentially be used for biowarfare, which Russia has long claimed are present in Ukrainian labs that receive U.S. support, Reuters reported.

Specifically, earlier this week, Russian foreign ministry spokesperson Maria Zakharova repeated Russia's long-standing claim that the U.S. operates a biowarfare lab out of Ukraine, Reuters reported on March 9. Zakhorova claimed that Russian forces had discovered documents in Ukraine that provided evidence of the Ukrainian health ministry ordering the destruction of samples of plague, cholera, anthrax and other pathogens before Feb. 24, the start of the invasion. The U.S. and Ukraine have both denied these claims.

"Russia has been going on about the labs in Ukraine for some years now. I have seen no evidence to support Russia's claims," Dr. Alastair Hay, professor emeritus of Environmental Toxicology at the University of Leeds, told the Science Media Centre, an organization that provides expert comments from scientists on timely issues and science-related news.

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Following Zakharova's statement, Dmitry Chumakov, a Russian deputy United Nations (UN) ambassador, repeated her accusation on March 9, The Associated Press (AP) reported. Then, Russia made a formal request that the UN Security Council meet to discuss the "military biological activities of the U.S. on the territory of Ukraine." The council scheduled said meeting for Friday morning (March 11).

"This is exactly the kind of false flag effort we have warned Russia might initiate to justify a biological or chemical weapons attack," Olivia Dalton, spokesperson for the U.S. Mission to the United Nations, said March 10, according to the AP. "We're not going to let Russia gaslight the world or use the UN Security Council as a venue for promoting their disinformation."

The WHO, who again works with Ukrainian labs, previously stated that "they are unaware of any activity on the part of the Ukrainian government which is inconsistent with its international treaty obligations, including on chemical weapons or biological weapons," UN spokesman Stéphane Dujarric said on March 10, according to the AP.

"Developing the agents Russia alleges Ukraine is working on would be a clear violation of the Biological Weapons Convention," Hay told the Science Media Centre. "The U.S. is actually trying to beef up the convention and make it fit for purpose … So, it would be highly unusual for the U.S. to be doing what Russia claims."

Originally published on Live Science.