A Ukrainian diplomat told the UN Security Council that he fears it is “being manipulated by the Russian Federation” during a meeting on Friday.
Russia called the emergency meeting to discuss unsubstantiated claims that Ukraine is preparing to use biological weapons, with the help of the US.
Ukraine’s permanent representative to the UN, Sergiy Kyslytsya, told members that a false narrative was being pushed by Russia and said it had “shot itself in the foot” by calling the meeting.
There are fears Russia could use chemical weapons in Ukraine in a “false flag” attack to provide a retrospective justification for its invasion.
Mr Kyslytsya also urged the UN Security Council to “address war crimes and crimes against humanity that the Russian Federation commits on a daily basis” since the invasion began on February 24.
He listed a number of examples that have “shocked the world” including the attack on the maternity hospital in Mariupol.
At least three people - including a six-year-old - are reported to have been killed in the air strike, and 17 other were injured in the attack on Wednesday.
He also said Russian forces had “almost destroyed Mariupol, one of the most beautiful cities” on the Sea of Azov.
According to the city’s council, 1,582 civilians had been killed in Mariupol since the invasion began, 16 days ago.
During his address, Mr Kyslytsya told of how “Ukrainian cities are being razed to the ground” and people are “being buried in mass graves”.
“The sooner the aggressor is stopped, the safer our world will be”.
He ended his address by reading an open letter from 194 Nobel Laureates who were expressing support for Ukrainian people and calling for the “free and independent state of Ukraine as it faces Russian aggression”.
Meanwhile, the UK’s permanent representative to the UN accused Russia of bringing about “wild, completely baseless and irresponsible conspiracy theories”.
Dame Barbara Woodward said Russia must not be allowed to “abuse its permanent seat” on the council “to spread disinformation and lies”.
“Russia has today brought into the security council a series of wild, completely baseless and irresponsible conspiracy theories,” she said.
“Let me put it diplomatically: they are utter nonsense.”
She added: “We do not sit in this chamber to be an audience for Russia’s domestic propaganda.
“And we should not allow Russia to abuse its permanent seat to spread disinformation and lies and pervert the purpose of the security council.”
Earlier, Prime Minister Boris Johnson expressed fears Russia was spreading a “fake story” that the US or the Ukrainians had chemical weapons in Ukraine as a pretext for an atrocity.
