The United Nations on Friday said it was not aware of any biological weapons programme in Ukraine.
Meanwhile, Washington and its allies voiced concerns Russia was spreading the unproven claim in order to launch its own biological or chemical attacks.
Russia called the meeting of the 15-member UN Security Council to reassert its unsubstantiated accusation that Ukraine ran biological warfare laboratories with US support.
The move risked backfiring on Moscow as members rejected the assertions as "a lie" and "utter nonsense" and used the session to amplify accusations that Russia has deliberately targeted and killed hundreds of civilians in its 15-day-old invasion that Russian President Vladimir Putin calls "a special military operation."
Izumi Nakamitsu, the UN High Representative for Disarmament Affairs, told the council that the United Nations is "not aware" of any biological weapons programme in Ukraine, which ratified an international ban on such arms, as has Russia.
The Russian envoy to the United Nations, Vasily Nebenzya, repeated the claim - without providing evidence - that Ukraine ran biological weapons laboratories with US Defense Department support.
Under a 2005 agreement, the Pentagon has assisted several Ukrainian public health laboratories with improving the security of dangerous pathogens and technology used to research.
Those efforts have been supported by other countries and the World Health Organisation.
The US envoy to the United Nations, Linda Thomas-Greenfield, said Washington was "deeply concerned" that Russia called the session as a "false flag effort" aimed at laying the groundwork for its own use of biological or chemical weapons in Ukraine.
Although she did not immediately provide evidence of an imminent threat during the meeting of the 15-member council, she said: "Russia has a track record of falsely accusing other countries of the very violations that Russia itself is perpetrating."
She added: "We have serious concerns that Russia may be planning to use chemical or biological agents against the Ukrainian people."