"It was like a true concentration camp."

This is how Oleksandr, a 49-year-old man from Mariupol, described where he and his wife Olena were taken in by Russian security officers. Speakingto a reporter for the BBC, the couple was fingerprinted, photographed and interrogated for hours, and their phones searched for material that could somehow identify them as “Nazis.”

But there is another name given to these locations, and the process, that have been set up to handle Ukrainians taken into custody in areas occupied by pro-Russian separatists: They’re called: “filtration camps.”

Since February 24, more than one million people have passed through these facilities, facing brutal conditions, passports stripped and sometimes tortured, according to Ukrainian authorities.

Michael Carpenter, U.S. ambassador to the Organization for Security and Cooperation in Europe (OSCE), said "at least several thousand" Ukrainians have been abducted and processed in the camps.

Soviet relic

They are called filtration camps because Russian security officers use them to screen civilians, and those who do not pass the filtering process are reportedly taken to Russia or to occupied territories of Donetsk. Witnesses have told Die Welt that they saw people blindfolded and handcuffed, put on buses and driven away.

Like concentration camps constructed by Nazis, and others, the “filtration” facilities recalls a brutal history. First established by Joseph Stalin in the USSR at the end of World War II, filtration camps received all prisoners of war, prisoners of German concentration camps, all men of conscription age who during the war simply lived in the occupied territories or representatives of local authorities were sent to the camps.

Though there were some good-faith efforts to identify individuals in the immediate post-War chaos, the filtration camps would eventually include brutal interrogations, torture, years of imprisonment, and hard labor in the Gulag camps — that's what awaited those who did not prove their loyalty to the Soviet authorities.

Civilians are taken from bombed-out cities with the promise of being evacuated.

Even before the conflict with Ukraine, there have been other revivals of filtration camps in post-Soviet times. In Chechnya, according to Russia-born human rights group Memorial, at least 200,000 people, one-sixth of Chechnya's entire population, passed through the camps, subjected to beatings, torture, and summary executions.

Satellite images/Maxar Technologies

Satellite image of one of the filtration camps near Mariupol

Psychological and physical torture

In Ukraine, the methodology of Soviet filtration camps began as early as 2014 in the Donbas: from the very moment of the occupation, "suspicious" citizens were summoned for interrogations, and there are many known cases where they were held for months and years in captivity, too often dying of torture and disease.

Thanks to the testimonies of people like Oleksandr and Olena who managed to break free, journalists know the details of life in these camps. Civilians are taken from bombed-out cities, after weeks in hiding, with the promise of being evacuated.

They are forced to sleep on the floor in unheated rooms, sometimes in such tight quarters that it is impossible to lie down. There is very little food and water, and no access to medical care. They are regularly tortured psychologically and physically, facing threats of reprisals against their relatives and demands to turn in their friends. Some have their passports confiscated. Families have been separated.

The filtration camps acquired a massive, organized character after the invasion of Ukraine on February 24. The existence of several camps is known in the area of the besieged port city of Mariupol, with satellite images showing that a camp with at least 30 tents was set up within a week, as well as in several cities in Donbas and Crimea.

Filtration camps are also the place from which Ukrainian citizens can voluntarily evacuate into Russian territory — though most times they are forcibly pushed to do so, with no options to evacuate to Ukrainian territories given.

Anna Voevodina, a Mariupol-born lawyer now living in Barcelona, is helping her compatriots who were brought to Russia using a Telegram group called “Deportation to Russia”, which now has around 900 members, Die Welt reports.

Thomas W. Morley/ZUMA

Ex Soviet military camp now the largest Chechen refugee comunity in Pankisi Gorge.

Prove your loyalty

Those who have not proven their loyalty to the Russian authorities are at best sent to forced settlements in remote regions of Russia, while those who remain in Ukraine are forced to work on debris removal, collecting corpses, bagging them, and digging graves.

Russia under Putin looks more and more like the Soviet Union under Stalin.

Such work is often the only opportunity for residents of the occupied territories to receive humanitarian aid for themselves and their families. Also, only after successfully passing the filtration camp can Ukrainians receive passes that allow them to move around the city or region, reports Ukraine’s daily Livy Bereg.

Fear is spreading for those “judged to have an allegiance” to Ukraine, said U.S. Ambassador Carpenter referring to reports indicating that people were transferred to Russian-occupied territories in Donbas, and their traces often lost.

Russia under Putin looks more and more like the Soviet Union under Stalin, and one might be horrified, but not necessarily surprised. The manual for persecution and human control was always right on the shelf.