The United States has accused Russia of war crimes through the forcible transfer up to 1.6 million Ukrainians to Russian-controlled territory in the current conflict, prompting senior UN officials to demand international access to the so-called filtration camps.
Moscow denied the charge and said millions of Ukrainians had chosen to go to Russia or Russia-controlled areas and were "living freely and voluntarily" there.
The U.S. ambassador to the UN, Linda Thomas-Greenfield, told a UN Security Council meeting late on September 7 that Russia and its proxies were inflicting "a series of horrors" in a process overseen by officials from President Vladimir Putin's office.
"The forcible transfer or deportation of protected persons from occupied territory to the territory of the occupier...constitutes a war crime," Thomas-Greenfield said.
The U.S. envoy said official Russian sources suggest that its authorities or allied Ukrainian separatists have "interrogated, detained, and forcibly deported" between 900,000 and 1.6 million Ukrainians to Russia since the Russian invasion in late February.
SEE ALSO: Russia Filtration Centers Map Society In Ukraine's Occupied Regions Ahead Of 'Referendums'She said more than 1,800 children had been transferred from Ukrainian territory to Russia in July alone.
Thomas-Greenfield said the Russian "aim [is] to identify individuals Russia deems insufficiently compliant or compatible to its control" and "to prepare for an attempted annexation" of Ukrainian territory.
Russia-backed separatists who have controlled swaths of the Luhansk and Donetsk regions of eastern Ukraine since 2014 have already tried to declare independence from Ukraine.
Since Russia's full-scale invasion of Ukraine in late February, occupation leaders installed by Russia have since vowed to hold referendums on joining Russia in other areas.
Kyiv and Western leaders have said any such votes under occupation are illegal and illegitimate.
Russian UN Ambassador Vassily Nebenzia called the accusations part of a "disinformation campaign" and said Ukrainians who travel to Russia undergo "a registration rather than filtration procedure."
SEE ALSO: Zelenskiy Confirms Recapture Of Towns In Northeast As Referendum Rescheduled In Occupied Southern Regions“They are living freely and voluntarily in Russia, and nobody is preventing them from moving or preventing them leaving the country,” Nebenzia said.
Many accounts by Ukrainian civilians, including children, have described humiliating and intrusive screenings at checkpoints and other filtration camps run by Russian troops or pro-Russian Ukrainian fighters.
Thomas-Greenfield said "there's a simple way to know if any of this is true," adding, "Let the United Nations in.”
She called for access for independent observers and NGOs and humanitarian efforts to "let the world see what is going on."
UN political chief Rosemary DiCarlo said the persistent allegations "of forced displacement, deportation, and so-called filtration camps run by the Russian Federation and affiliated local forces" are "extremely disturbing."
WATCH: 'You Are Russian Now': Ukrainian Family Recalls Deportation To Russia
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'You Are Russian Now': Ukrainian Family Recalls Deportation To Moscow
DiCarlo also urged UN access to Ukrainians living in Russian-controlled areas.
She said the International Committee of the Red Cross and the UN Human Rights Monitoring Mission in Ukraine "must have unimpeded access to all individuals detained in relation to the ongoing war."
UN Assistant Secretary-General for Human Rights Ilze Brands Kehris asked Moscow to provide her Geneva-based office with access to all detention sites and said any adoptions of Ukrainian children would contravene the Geneva Convention.
More than 13 million Ukrainians have been displaced by Russia's unprovoked invasion, with both sides vowing to fight on amid death tolls in the tens of thousands with many times that number injured.