https://holocaust.com.au/the-facts/the-outbreak-of-world-war-ii-and-the-war-against-the-jews/what-the-allies-knew/
As early as May 1942, and again in June, the BBC reported the mass murder of Polish Jews by the Nazis. Although both US President, Franklin Roosevelt, and British Prime Minister, Winston Churchill, warned the Germans that they would be held to account after the war, privately they agreed to prioritise and to turn their attention and efforts to winning the war. Therefore, all pleas to the Allies to destroy the death camp at Auschwitz-Birkenau were ignored. The Allies argued that not only would such an operation shift the focus away from winning the war, but it could provoke even worse treatment of the Jews. In June 1944 the Americans had aerial photographs of the Auschwitz complex. The Allies bombed a nearby factory in August, but the gas chambers, crematoria and train tracks used to transport Jewish civilians to their deaths were not targeted.