By Christian Fraser
BBC News, Rome
The man who later became Pope John XXIII tried in vain to challenge the Vatican's perceived indifference to the Nazi Holocaust, a new study has found.
Pope John XXIII was earlier the papal nuncio to Istanbul
Papers and diaries show then Archbishop Giuseppe Roncalli posted an urgent telegram in 1944 to Pope Pius XII on the atrocities at Auschwitz.
The telegram's date contradicts the Vatican's official version of when it received a report.
The new insight comes from the papers of a Jewish emissary, Haim Barlas.
He had befriended Archbishop Roncalli, then the papal nuncio to Istanbul, in the 1940s.
The exchange of letters between Barlas and Roncalli, mostly in French, was recently uncovered in a private collection in Israel.
The letters show that Roncalli was frustrated by the Vatican's silence in the face of what was emerging in Europe.
They show that in 1943, the archbishop took it upon himself to write to the president of Slovakia asking him to stop the Nazi deportation of Jews.
On 23 June 1944, Barlas passed Roncalli a chilling 30-page report.
The document, now known as the Auschwitz protocols, had been compiled by two Jews who had escaped the camp that April.
The archbishop quickly scribbled a synopsis of the report and sent it by telegram.
His message made clear that the camp's purpose was the mass killing of Jews.
The date the telegram was sent contradicts the Vatican's official version that it only received details of the report in October 1944.
Vatican officials, when asked about the alleged discrepancy, suggested the question be directed to historians of the period.
But while all of the archbishop's correspondence with his Church superiors has been preserved in the Vatican archives, the part that could clarify when he sent the details has not been made available to scholars.