In May 1942, a Bund underground activist in Warsaw, Leon Feiner, sent a preliminary report to London containing information on the murder of Jews in various parts of Poland. The report traced the path of the murder actions: town after town, district after district, month by month. It described the extermination center at Chelmno, including the gas vans, and estimated the number of Jews whom the Germans had murdered in Poland by May at 700,000 (the figure was much higher). Feiner stated that, in the absence of substantive actions to halt the murders, no Jews would survive in Europe by the end of the war. The report also urged the Allies to adopt a policy of retaliation against German citizens residing in Allied countries.
Feiner´s report was forwarded to the media and to the political echelon, including the Polish government-in-exile in London, and became the decisive factor in the eruption of reports on the mass murder and their assimilation in public opinion.
On June 2, the BBC broadcast the main contents of the report, including the estimate of the 700,000 murdered Jews. However, it did not stress the conclusion of the report: that the program to murder all the Jews was already being carried out. A week later, the Polish government-in-exile presented the findings of the report to the Allied governments in an official missive. On June 25, Samuel Zygelbojm, one of two Jewish representatives in the Polish government, released the entire document to the press. The Allied governments did not respond to these efforts, but newspapers began to carry the information with greater frequency. The Boston Globe and The New York Times presented prominent reports, including the assessment that the Jewish population was being systematically annihilated.
Shortly after this, two authoritative voices in Britain reinforced the Bund´s announcement. At a press conference, the Minister of Information, Brendan Bracken, stated that 700,000 people, all of them Jewish, had been murdered in Poland. He also proclaimed that, once the war ended, the "United Nations" would ensure the rapid and severe punishment of the persons responsible for the grievous war crimes that had been perpetrated in Poland against Jews and Poles alike. He fiercely criticized those who regarded the murder reports as propagandistic hyperbole. The truth is solid, he said vehemently, and the murder will eventually come to light.