Vladimir Putin has been compared to Hitler amid reports thousands of Ukrainians to leave their besieged city bound for Russian labour camps.
Officials say up to 5,000 people have been made to leave the city of Mariupol, which has seen intense fighting over the past week, and sent to south-western Russia.
The move has provoked chilling parallels with Nazi concentration camps in the 1930s and 1940s, with the Russian invaders accused of following "the logic of Nazi Germany".
City mayor Vadym Boychenko likened the move to the actions of Hitler's Third Reich, saying it was "hard to imagine" it could happen in the 21st century.
It is claimed that Russian troops trawled through the phones and documents of residents before telling some they were being deported to Russia.
Mr Boychenko said: "It is known that the captured Mariupol residents were taken to filtration camps, where the occupiers checked people's phones and documents.
"After the inspection, some Mariupol residents were redirected to remote cities in Russia; the fate of others remains unknown.
"What the occupiers are doing today is familiar to the older generation, who saw the horrific events of World War Two, when the Nazis forcibly captured people.
"It is hard to imagine that in the 21st century people would be forcibly deported to another country.
"Not only are Russian troops destroying our peaceful Mariupol, they have gone even further and started deporting Mariupol residents."
Ukrainian MP Inna Sovsun told Times Radio that Russia was following "the logic of Nazi Germany".
She said: "From what we know from the city mayor and the city council, is they are taking Ukrainian citizens.
"They are sending them through what are called the 'filtration camps' and then they are being relocated to very distant parts of Russia, where they are being forced to sign papers (saying) that they will stay in that area for two or three years and they will work for free in those areas."
Ms Sovsun agreed when it was put to her that what she was describing was "effectively slave labour".
British Foreign Secretary Liz Truss has condemned the "abduction and deportation" of Ukrainians.
She said she was "appalled" by the reports and said Putin must be "held to account" for his treatment of civilians during the invasion.
Mariupol is in the throes of a humanitarian emergency after being encircled by Russian troops, cut off from energy, food and water supplies and facing a relentless bombardment.
On Sunday, city authorities said a bomb destroyed an art school where 400 people had taken shelter, with rescuers searching for people possibly trapped under the rubble.
Only days before the shelling, there was a separate attack on a theatre in the city where more than 1,000 people were said to have been bunkered.
Speaking at the Tory spring conference, Boris Johnson warned that a Putin victory in Ukraine would be the "beginning of a new age of intimidation across the whole of eastern Europe".
It would give "the green light for autocrats everywhere", he said.
