At least 500 Brits and Americans were murdered in the extermination camp Treblinka, built in Poland by Nazi Germany during the Second World War, newly published declassified materials from the Russian Defense Ministry’s central achieves reveal.

One of the documents, declassified by the Russian military, states that after a trip to the notorious concentration camp set up in July 1942 between Warsaw and Bialystok, a journalist from the military newspaper “Za Rodinu” reported to the political officer of the 70th Army that along with Jews, Romani, Poles, and other people persecuted by the Nazis were being killed there.

The document cited says that according to reports, in 1942, the Germans ordered all Britons and Americans to gather on Warsaw’s prison square for a prisoner of war swap. Instead of being swapped for German prisoners, they were taken to the camp where many Jews had been brought. Like thousands of others before them, they were immediately ordered to the camp’s so-called bathhouse and killed.