A mass grave containing the ashes of thousands of people has been discovered near a former Nazi concentration camp in Poland, according to the country’s Institute of National Remembrance (IPN).

The remains were unearthed near the Soldau concentration camp, now known as Dzialdowo, which is located north of the capital Warsaw, the institute said in a statement Wednesday.

The IPN investigates crimes committed during the Nazi occupation of Poland.

The institute noted that Germany targeted Polish state elites at the camp, adding "it’s the evidence of how thoroughly the Germans tried to obliterate the traces of genocide they committed in Eastern Europe."

Other media outlets put the number of victims in the mass grave at 8,000 due to the 15.8 tons of human ashes found.

The camp was built by Nazi Germany during World War II when it occupied Poland. It was used as a transit camp and for the internment and extermination of Jews, political opponents and Polish political elite.