Lyudmyla Denisova, Ukraine's ombudswoman, has accused Moscow of forcibly removing hundreds of thousands of civilians from obliterated Ukrainian cities to Russia to put pressure on Kyiv to surrender.
Denisova said on March 25 that 402,000 people, including 84,000 children, had been taken against their will to Russia, where some may be used as "hostages" to press Ukraine to give up.
The Kremlin gave nearly identical numbers for those who have been relocated, but claimed that they wanted to go to Russia.
Ukraine's separatist-controlled eastern regions are predominantly Russian-speaking, and some people there have supported close ties to Moscow.
Russian Colonel General Mikhail Mizintsev said the roughly 400,000 people evacuated to Russia since the start of the invasion were from the Donetsk and Luhansk regions in eastern Ukraine, where Moscow-backed separatists have been fighting for control for nearly eight years.
Russian authorities say they are providing accommodation and dispensing payments to the evacuees.
But Donetsk region Governor Pavlo Kyrylenko said that "people are being forcibly moved into the territory of the aggressor state."
Denisova said those removed by Russian troops included a 92-year-old woman in Mariupol who was forced to go to Taganrog in southern Russia.
Ukrainian officials said that the Russians were taking people's passports and moving them to "filtration camps" in Ukraine's separatist-held east before sending them to various distant, economically depressed areas in Russia.
Among those taken, Ukraine's Foreign Ministry claimed, were 6,000 residents of Mariupol, the besieged port city in the country's southeast. Russian troops were confiscating identity documents from an additional 15,000 people in a section of Mariupol under their control, the ministry said.