The “Mass Extermination of Jews in German Occupied Poland” was a brochure published by the Polish government-in-exile on December 10, 1942, and sent to the foreign ministers of the 26 government signatories of the Declaration by United Nations. It was the first official document informing the Western public about the Holocaust in German-occupied Poland.
The brochure contains reports and documents about the Holocaust in Poland. The most important item was Raczyński’s Note, by Edward Bernard Raczyński, the foreign minister of the Polish government-in-exile. Based on intelligence from the Home Army’s Jewish Affairs Bureau, Raczyński discussed the Germans’ initial shooting executions and subsequent lethal gassings of Polish Jews. It was known that Jews deported from the Warsaw Ghetto were taken to Treblinka, Bełżec, and Sobibor, which the Polish underground described as “extermination camps.” Raczyński said that one-third of the three million Polish Jews had already been killed.
The brochure also contained the text of the Joint Declaration by Members of the United Nations of December 17, 1942, and an excerpt of a statement by Deputy Prime Minister Stanisław Mikołajczyk of November 27, 1942.
Though the document contained extensive information on the persecution and murder of Jews in Poland, its effect was limited because many people outside German-occupied Europe found it difficult to believe the Germans were systematically exterminating Jews.
Modern commentators have raised questions as to why the report was not published sooner, because the Polish government-in-exile had been kept apprised of the events in Poland by the underground state, the Jewish Labor Bund, and others. Emanuel Ringelblum, chronicler of the Warsaw Ghetto, accused the Polish underground state of refusing to pass along information on the murder of Jews; he believed they did so only after repeated exhortations by the Jews. His main complaint was with the government-in-exile, which knew but stayed silent about the murder of the Warsaw Jews from July to September 1942. According to Ignacy Schwarzbart, one of two Jewish members of the government-in-exile, the Poles feared that bringing attention to the suffering of Jews would distract the Allies from the suffering of Poles.
Source: “The Mass Extermination of Jews in German Occupied Poland,” Wikipedia.