The United Nations on Friday said it had no evidence Ukraine had a biological weapons program while Washington and its allies accused Russia of spreading the unproven claim as a possible prelude to launching its own biological or chemical attacks.
Russia called the meeting of the 15-member UN Security Council to reassert through its envoy Vassily Nebenzia, without providing evidence, that Ukraine ran biological weapons laboratories with US Defense Department support.
Member countries called the claim "a lie" and "utter nonsense" and used the session to accuse Russia of deliberately targeting and killing hundreds of civilians in Ukraine, assertions that Russia denies in a 15-day offensive it calls "a special military operation."
Izumi Nakamitsu, the UN High Representative for Disarmament Affairs, told the council the United Nations is "not aware" of any biological weapons program in Ukraine, which joined an international ban on such arms, as has Russia and the United States along with 180 other countries.
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 Organization.
The WHO told Reuters on Thursday that it had advised Ukraine to destroy high-threat pathogens housed in its public health laboratories to prevent "any potential spills" that would spread disease among the population.
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" to lay the groundwork for its own use of biological or chemical weapons in Ukraine.
Although she provided no evidence of an imminent Russian threat during the meeting, 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.
"The intent behind these lies seems clear, and it is deeply troubling," she said. "We believe Russia could use chemical or biological agents for assassinations, as part of a staged or false flag incident, or to support tactical military operations."
'The council should not be served with fantasies'
Responding to Ms Thomas-Greenfield's statement, Mr Nebenzia recalled then-US Secretary of State Colin Powell's 2003 Security Council testimony when he presented what Washington claimed was proof that Iraq was hiding banned weapons of mass destruction programs.
The United States used the assertion, which turned out to be false, to justify its 2003 US invasion of Iraq.
Answering the Russian envoy, Ms Thomas-Greenfield said: "I know that you expect me to respond but we're not going to give any more airtime to the lies that you're hearing today."
US allies echoed Ms Thomas-Greenfield's concerns that Russian President Vladimir Putin's government was spreading the claim of a US-backed bioweapons program in Ukraine to prepare its own chemical or biological attacks in Ukraine.
"The council should not be served with fantasies or starry-eyed stories, but with proof independently verified and collaborated," said Ferit Hoxha, the ambassador of NATO member Albania.
"We should therefore be very worried that in spreading such disinformation, a crescendo of allegations about weapons of mass destruction could serve as yet another pretext for Russia to prepare the ground and use chemical or biological weapons during its ongoing invasion of Ukraine," he said.
In Irpin, a strategic suburb west of Kyiv, desperate civilians try to flee bombings and the arrival of Russian troops. Source: ABACA / AAP
French Ambassador Nicholas de Riviere noted, as did several other envoys, that Russia allegedly used a nerve agent in failed attempts to kill jailed opposition leader Alexei Navalny and a former Russian intelligence officer, Sergei Skripal, who defected to Britain, and his daughter.
Russia denies these allegations.
Speaking to reporters earlier on Friday, US President Joe Biden warned Russia that it would pay a "severe price" if its military should use chemical weapons against Ukraine.
2.5 million flee Ukraine
Two and a half million people have fled Ukraine since Russia invaded and another two million have been internally displaced by the war, the United Nations said Friday.
The UN Refugee Agency's chief Filippo Grandi blamed the mass displacement on what he called a "senseless war" that began on 24 February.
"The number of refugees from Ukraine - tragically - has reached today 2.5 million," UNHCR chief Grandi tweeted.
"We also estimate that about two million people are displaced inside Ukraine. Millions forced to leave their homes by this senseless war."
Paul Dillon, spokesman for the UN's International Organization for Migration, said the two and a half million people who had fled Ukraine included 116,000 nationals from other countries.
Before Russia invaded, more than 37 million people lived in Ukrainian territory under the control of the central government in Kyiv.
More than half of those who have fled have gone to Poland.
Civilian targets hit as Russian forces near Kyiv
Russian strikes hit civilian targets in central Ukraine's Dnipro city on Friday, as Moscow's troops edged closer to the capital Kyiv that, according to its Mayor Vitali Klitschko, has lost half of its estimated 3.5 million population since the war began.
Officials in Kyiv said the capital was being transformed into a "fortress".
Hundreds of thousands of civilians remained trapped and under fire in Ukrainian cities, including besieged Mariupol, after the first talks between Moscow and Kyiv's top diplomats ended Thursday without any progress.
In the early hours of Friday, Russian warplanes carried out what appeared to be the first direct attack on Dnipro, killing one person, emergency services said in a statement.
Bombed buildings in a residential neighbourhood near Kharkiv Metro Station on 10 March 2022. Source: Anadolu / Getty Images
Meanwhile two Ukrainian soldiers were killed and six wounded in Russian strikes on the Lutsk military airport in the northwest, local authorities said.
Russian forces are currently encircling at least four major Ukrainian cities, while the capital Kyiv is increasingly at risk of being surrounded.
The UN said some 2.5 million refugees have left Ukraine since Russia shocked the world by invading its neighbour on 24 February.
'Nowhere to run'
The Ukrainian military warned Russia was trying to "block" Kyiv by taking out defences to the west and northwest of the capital, adding that there was also a risk to Brovary on the east.
Kyiv's mayor Vitali Klitschko said Thursday that half the city's population had fled and the capital "has been transformed into a fortress".
"Every street, every building, every checkpoint has been fortified."
The northwest suburbs, including Irpin and Bucha, have endured days of heavy bombardment but Russian armoured vehicles are also advancing on the northeastern edge of Kyiv.
Ukrainian soldiers described fierce fighting for control of the main highway leading into the capital, and AFP reporters saw missile strikes in Velyka Dymerka just outside Kyiv's city limits.
"It's frightening, but what can you do?" said Vasyl Popov, a 38-year-old advertising salesman.
"There is nowhere to really run or hide. We live here."
Britain's defence ministry said in an intelligence update that "Russian forces are committing an increased number of their deployed forces to encircle key cities".
"This will reduce the number of forces available to continue their advance and will further slow Russian progress," it said.
Russian President Vladimir Putin on Friday backed plans to allow volunteers, including from abroad, to fight in what Moscow calls a "special military operation" in Ukraine.
The Russian army this week admitted conscripts were taking part, after Putin previously said only "professional" soldiers were involved.
Putin backs plans to send volunteer fighters to Ukraine
Mr Putin on Friday backed plans to allow volunteers, including from abroad, to fight in Ukraine, where he has sent thousands of Russian troops in what he calls a "special military operation".
"If you see that there are people who want on a voluntary basis (to help east Ukraine's separatists), then you need to meet them halfway and help them move to combat zones," Mr Putin told Defence Minister Sergei Shoigu during a televised security council meeting.
According to Shoigu, more than 16,000 volunteers - mostly from the Middle East - have appealed to join the military action.
"As for the supply of arms, especially Western-made, which ended up in the hands of the Russian army, of course I support the possibility of transferring them to the military units of DNR and LNR," Putin said referring to the breakaway Donetsk and Lugansk People's Republics in Ukraine's east.
Mr Putin also ordered that Shoigu prepare a separate report on strengthening Russia's western borders "in connection to the actions that NATO countries are taking in this direction".