The mayor of the besieged city of Mariupol said that roughly 31,000 residents have been forcibly deported and sent to Russian "filtration camps" in occupied eastern Ukraine.

Mayor Vadym Boychenko said in a Telegram post Friday that he had "verified" that Ukrainians from the southern port city were being taken "at gunpoint" to a camp in Novoazovsk – a Ukrainian border town 35 miles from Mariupol and just 9 miles from the Russian border. 

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FILE - Marianna Vishegirskaya stands outside a maternity hospital that was damaged by shelling in Mariupol, Ukraine, Wednesday, March 9, 2022. (AP Photo/Mstyslav Chernov, File)

FILE - Marianna Vishegirskaya stands outside a maternity hospital that was damaged by shelling in Mariupol, Ukraine, Wednesday, March 9, 2022.  (AP Photo/Mstyslav Chernov, File)

Novoazovsk is located in the Donetsk People’s Republic – a breakaway region in Ukraine’s most eastern front that has been backed by Russian forces and engaged in armed conflict with the Ukrainian army since 2014.

Just days before the February invasion, the Russian State Duma passed a bill officially recognizing the self-proclaimed Donetsk and Luhansk People's Republics, which was then signed by Russian President Vladimir Putin. 

Boychenko said Ukrainians have been at the camps for weeks. 

"Filtration is very strict - fingerprints are taken, as well as biometrics. They force people to sign various documents," he described, according to a translation by a Ukrainian news agency.

The mayor noted that government employees have been treated particularly harshly. 

U.S. Ambassador to the United Nations Linda Thomas-Greenfield said this week that she has seen "credible reports" that support the filtration camp claims and noted that Ukrainians are being separated from their families and stripped of their passports and identification cards.

A view of the Mariupol theater damaged during fighting in Mariupol, in territory under the government of the Donetsk People's Republic, eastern Ukraine, Monday, April 4, 2022.  (AP Photo/Alexei Alexandrov)

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"I do not need to spell out what these so-called filtration camps are reminiscent of. It’s chilling, and we cannot look away," she said in an address to the UN Security Council, alluding to Nazi-era concentration camps. "Every day we see more and more how little Russia respects human rights."

The Mariupol City Council has estimated that over 100,000 residents are still trapped inside the partially occupied city, but evacuation efforts remain stalled.

Humanitarian corridors have allegedly been agreed to by Russian troops, but aid organizations have been unable to reach the city that has been rocketed by shelling for more than six weeks. 

Boychenko said in late March that 90 percent of all residential buildings had been destroyed and thousands are without water, electricity or heat. 

An estimated 5,000 Mariupol residents have been killed according to the mayor, and reports have surfaced that a mobile crematorium is being used by Russian troops to cover up their alleged war crimes.  

"The world has not seen the scale of the tragedy in Mariupol since the existence of the Nazi concentration camps. Russia-occupation forces turned our entire city into a death camp," Boychenko said this week. "This is the new Auschwitz and Majdanek."

Dead bodies are placed into a mass grave on the outskirts of Mariupol, Ukraine, Wednesday, March 9, 2022, as people cannot bury their dead because of the heavy shelling by Russian forces.  (AP Photo/Evgeniy Maloletka)

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