The Vatican today launched initiatives to mark the fiftieth anniversary of the death of Pius XII, seen as part of a campaign to counter a persistent image of the wartime Pope as a world leader who "remained silent" during the Nazi Holocaust.

Father Federico Lombardi, the Vatican spokesman, said there was "no direct connection" between planned exhibitions and conferences in the autumn commemorating Pius XII's life and times and controversial proposals to put him on the road to sainthood by beatifying him, the step before canonisation.

However, Monsignor Salvatore Fisichella, rector of the Lateran University, which is co-hosting the commemorations, said the aim was to "clarify the complexity" of his career. Monsignor Fisichella, who today replaced Monsignor Elio Sgreccia as head of the Pontifical Academy for Life and was promoted to archbishop, said the image of Pius XII as indifferent to Jewish persecution by the Nazis persisted "depite the evidence" because of "collective inertia".

Monsignor Walter Brandmuller, head of the pontifical historical committee, said Pius XII's career was "too often seen in terms of politics rather than his Petrine ministry". Giovanni Maria Vian, editor of L'Osservatore Romano, the Vatican newspaper, said he hoped a "more rounded" picture of Pius XII would emerge.

The Pius XII conference in November, organised by the Lateran and Gregorian Pontifical Universities, will focus on the pontiff's 43 encyclicals and his spiritual and doctrinal teachings, or Magisterium, rather than his wartime role. Vatican officials said that the emphasis will be on the "continuity" between his thought and the reforms of the Second Vatican Council convened by his successor, Pope John XXII.

Father Lombardi said that Pave the Way, a New York-based Jewish organisation, was to bring a group of Jewish Holocaust survivors to Rome to thank Pope Benedict XI for Pius XII's efforts to save Jews during the Second World War. A new book by Gerard Noel, a former editor of the Catholic Herald, said that far from being anti Semitic, Pius XII performed exorcisms on Hitler in the middle of the night, believing the Nazi dictator to be possessed by the Devil.

In Pius XII: The Hound of Hitler Mr Noel said that Pius XII was "neither anti-Jewish nor pro-Hitler", but motivated by "huge ambition for the Catholic Church, which he believed to be the one true Church".

"Pius XII was a disaster for the Jews, not because he was anti-Semitic, but because he had great political ambitions," Mr Noel told The Jewish Chronicle. "His attitude was also moulded by the fact that he was a product of the pre-Vatican Council Church, which believed in the conversion of the Jews to Christianity."

He said that the Holy See's Concordat with the Third Reich in 1933, negotiated by Pius XII when he was Secretary of State as Cardinal Eugenio Pacelli, led directly to Hitler's ascent to power the same year. "In return for widespread material concessions for the Catholic Church in Germany, the Holy See guaranteed that German Catholics would refrain from all partisan political activity. This involved the disbandment, by papal directive, of the German Centre Party. The party held the balance of power, and without them, Hitler was able to assume supreme power."

Within days of the Concordat, "Hitler began his round-up of the Jews. And once he had signed the Concordat, Pius was afraid that if he criticised Hitler or Nazism, he would split the Catholic Church in Germany," Mr Noel said.

The book also describes the relationship between Pius XII and Sister Pasqualina, his German housekeeper, who was at his side for 40 years. "She was a very powerful and very enlightened woman, and was fervently against the Pope's alliances with Hitler and Mussolini, but he disregarded her advice over Hitler," Mr Noel said.

Pope Pius XII, who reigned from March 1939 until his death in October 1958, began his diplomatic career as papal nuncio in Munich and later in Berlin. He was made a cardinal and Secretary of State in 1929 by Pius XI, and drafted Pius XI's celebrated encyclical "Mit Brennender Sorge" which condemned the "idolatrous exaltation of race", a clear but indirect reference to Nazi ideology.

He was elected Pope after the death of Pius XI in February 1939, on the eve of the Second World War. In his wartime Christmas broadcasts on Vatican Radio Pius XII offered support for "those who, although personally blameless, have simply on account of their nationality and origin been killed or reduced to utter destitution."

However allegations that he failed to speak out explicitly against Hitler have dogged his beatification cause, opened in 1967. In May last year the Congregation for the Causes of Saints declared he had "heroic virtues", a step towards beatification, but the process remains stalled.

Both Jewish and Catholic scholars have complained that Vatican archives on Pius XII are only full accessible for the years up to 1939. Studies of the Pius XII controversy include John Cornwell's Hitler's Pope: The Secret History of Pius XII, published in 1999, and Rabbi David Dalin's The Myth of Hitler's Pope: How Pope Pius XII Rescued Jews from the Nazis, published in 2005.