According to a report by New York Times due to be published on Sunday, US researchers have catalogued 42,500 Nazi-run camps which were set up in Germany and throughout occupied Europe – tens of thousands more than previously thought.
Previous postwar estimates had put the number of Nazi camps and ghettos at about 7,000, wrote the paper.
Holocaust historians were shocked by the scale of the revelations, the result of a thirteen-year investigation by researchers at the United States Holocaust Memorial Museum. Beginning in 2000, researchers set out to document all the sites in Europe where the Nazis imprisoned, tortured and enslaved their victims between 1933 and 1945.
"The numbers are so much higher than what we originally thought," Hartmut Berghoff, director of the German Historical Institute in Washington told the paper.
"We knew before how horrible life in the camps and ghettos was, but the numbers are unbelievable," he said. Until now, historical records of the Nazi camps had been fragmented - this is the first study to document them in their entirety.
The research also highlights the variety of the Nazi-run camp network, which by the end of the war spanned from France to Russia, with the majority of sites clustered in and around Poland and Germany, wrote the paper.
During the war, the Nazis used the network to systematically imprison, enslave and murder millions of European Jews, homosexuals, Roma and Sinti, Poles, Russians and many other ethnic groups in Eastern Europe.
An estimated 15 to 20 million people died or were imprisoned in the camps, lead researchers Geoffrey Megargee and Martin Dean told the paper.
Pulling together data from 400 contributors, researchers unearthed not only death camps and euthanasia centres, but also thousands of forced labour, POW and transit camps, along with centres where pregnant women were forced to have abortions and brothels where women were forced to have sex with German soldiers.
The camps began appearing in Germany almost as soon as the Nazis came to power in 1933. The sheer number of them – 3,000 in Berlin and 1,300 in Hamburg alone – meant there could be no doubt that the Germans had known about their existence at the time, head researcher Dean told the New York Times.
“You literally could not go anywhere in Germany without running into forced labour camps, POW camps, and concentration camps,” said Dean. “They were everywhere.”