An Israeli scholar has discovered evidence that a Vatican emissary and future Pope tried to challenge the Catholic Church's perceived indifference to the Nazi mass murder of Europe's Jews during World War II. Searching the little-known papers of an Israeli emissary who worked to save Jews during the war, Dina Porat, a professor of Jewish history from Tel Aviv University, found evidence that that Giuseppe Roncalli - who later became Pope John XXIII - criticized the policies of Pope Pius XII, lobbied to save Jews and passed on information about the death camps at Auschwitz months earlier than the Vatican acknowledged receiving it. Pius XII, who was Pope during the war, has come under criticism for decades for his silence and that of his church in the face of the Holocaust, when six million Jews were killed by the Nazis in an official effort to wipe out the Jews of Europe. Porat, a prominent Holocaust scholar, researched the diaries and correspondences of Haim Barlas, an emissary dispatched by the Jewish Agency in the 1940s to save Jews in Europe. His papers are held in a private archive in Israel, the owners of which have refused to be publicly identified but who granted access to Porat. she said. Barlas's papers have significant historical value, Porat said, but have been unknown so far because the documents are not in an official archive and are mostly in Hebrew. In the 1940s, Barlas and Roncalli were both posted to Istanbul - Barlas as a Jewish Agency emissary and Roncalli as a Vatican nuncio, or ambassador. The two men became friends, Porat said, and their letters - mostly in French, a language both men spoke fluently - indicate that Roncalli "gently" expressed criticism of the Vatican's silence in the face of what was increasingly emerging as the Nazi genocide in Europe. In 1943, Porat found, following a request from Barlas, Roncalli wrote to the president of Slovakia asking him to stop the Nazi deportations of Jews to death camps. On June 23, 1944, Barlas received a copy of a chilling 30-page report that became known as the "Auschwitz protocols," compiled by two Jews who escaped from the camp that April. The report made it clear that the camp's purpose was the mass killing of Jews and others who the Nazis considered undesirable. At the time, the Nazis were in the midst of killing 400,000 Jews from Hungary. In his papers, Barlas wrote that he rushed a copy of the protocols to his friend Roncalli on June 24, and that Roncalli sent a synopsis to the Vatican by telegram that day. This contradicts the Vatican's official version, Porat said, which is that it received the report only in October 1944. Vatican officials, when asked about the alleged discrepancy in the dates, suggested that the question be directed to historians of that period. While many believe a concerted Vatican effort could have led to steps to stop the killing, Emma Fattorini, contemporary history professor at Rome's La Sapienza University, said the matter of "this month versus that month" was not critical. "The question is not, 'they knew or didn't know.' By now it's a well-grounded (fact) that the Vatican knew, just like everyone else," she said. All of Roncalli's correspondence with his church superiors has been preserved in the Vatican archives, Porat said - but the part that could clarify when he sent the protocols has not been made available to scholars. For years, the Vatican has struggled to defend its wartime pope, Pius XII, who had earlier served as a Vatican diplomat in Germany, against claims he did not do enough to save Jews from the Holocaust. Pius XII's 1939-1958 papacy spanned the war years, and Roncalli replaced him - as John XXIII - when he died. In 2003, the Vatican made available documents from the offices of the papal nuncios in Berlin and Munich in a bid to deflect contentions that the Vatican had been silent in the face of the Holocaust. The Vatican has insisted Pius XII had spearheaded discreet diplomacy that saved thousands of Jews.