Western countries accused Russia of spreading "wild" conspiracy theories at the United Nations Friday after Moscow's envoy told diplomats that America and Ukraine had researched using bats to conduct biological warfare.

Moscow called a meeting of the 15-member Security Council to repeat its previously made, unsubstantiated claims that Washington had funded biological weapons research in Ukraine.

Russia's ambassador to the UN, Vassily Nebenzia, said Kyiv had operated a network of 30 laboratories carrying out "very dangerous biological experiments" aimed at spreading "viral pathogens" from bats to people.

The pathogens included the plague, anthrax, cholera and other lethal diseases, Nebenzia said in Russian, without providing any evidence.

"Experiments were being conducted to study this spread of dangerous diseases using active parasites such as lice and fleas," he told diplomats.

Washington and Kyiv have denied the existence of laboratories intended to produce biological weapons in the country.

Izumi Nakamitsu, the UN's Under-Secretary-General of Disarmament Affairs, told the meeting the UN "was not aware of any biological weapons program in Ukraine."

British ambassador to the UN Barbara Woodward said Russia had used the Security Council to utter "a series of wild, completely baseless and irresponsible conspiracy theories."

"Let me put it diplomatically: they are utter nonsense. There is not a shred of credible evidence that Ukraine has a biological weapons program," she said.

Linda Thomas-Greenfield, the United States' envoy to the UN, said the US has helped Ukraine operate public health facilities that detect diseases like Covid-19.

"This is work that has been done proudly, clearly, and out in the open. This work has everything to do with protecting the health of people. It has absolutely nothing to do with biological weapons," she explained.

Thomas-Greenfield accused Russia of requesting the meeting "for the sole purpose of lying and spreading disinformation."

She said the United States was "deeply concerned" that Russia had called the session as part of a "false flag effort" for using chemical weapons of its own in Ukraine.

"Russia has a track record of falsely accusing other countries of the very violations that Russia itself is perpetrating," she said.

Russia's defense ministry on Thursday accused the United States of funding research into the development of biological weapons in Ukraine, which has faced an assault by tens of thousands of Russian troops since February 24.

The claim was later repeated by Russian Foreign Minister Sergei Lavrov.

In 2018, Moscow accused the United States of secretly conducting biological weapons experiments in a laboratory in Georgia, another former Soviet republic that, like Ukraine, has ambitions to join NATO and the European Union.