Pope Benedict on Thursday forcefully defended his wartime predecessor Pius XII against accusations that he did not do enough to help the Jews, saying Pius "spared no effort" on their behalf during World War II.

The pope spoke to members of the U.S.-based Pave the Way Foundation, a mixed Jewish-Catholic group which held a symposium in Rome on the papacy of Pius, who reigned from 1939 to 1958.

The symposium prepared a 200-page compilation of documents, diplomatic cables and newspaper clippings from the period -- some of them previously unpublished -- showing Pius did much to help Jews during the war and was thanked by Jewish leaders.

"Thanks to the vast quantity of documented material which you have gathered, supported by many authoritative testimonies, your symposium offers to the public forum the possibility of knowing more fully what Pius XII achieved for the Jews persecuted by the Nazi and fascist regimes," Benedict said.

"One understands, then, that wherever possible he spared no effort in intervening in their favor either directly or through instructions given to other individuals or to institutions of the Catholic Church," Benedict told the group at his summer residence south of Rome.

Some Jews have maintained that Pius did not do enough to save Jews, while the Vatican and those Jews who support him say he worked behind the scenes to help because more direct intervention would have worsened the situation.

But Benedict praised the symposium for drawing attention "to his many interventions, made secretly and silently, precisely because, given the concrete situation of that difficult historical moment, only in this way was it possible to avoid the worst and save the greatest number of Jews."

Gary Krupp, an American Jew who is president and founder of Pave the Way, told the pope the group's investigation "directly contradicts the negative perception of the pope's war time activities."

Camp survivors thanked the pope

Pope Benedict noted that in November 1945, some six months after the end of the war, 80 delegates of German concentration camps came to the Vatican to thank Pius.

The symposium's documents included numerous newspaper clippings of Jewish leaders thanking Pius during and after the conflict and former Israeli Prime Minister Golda Meir saying: "When fearful martyrdom came to our people in the decade of Nazi terror, the voice of the pope was raised for the victims."

The issue of Pius' papacy is one of the most difficult in Catholic-Jewish relations and the pope said that nearly five decades after his death "not all of the genuine facets of his diverse pastoral activity have been examined in a just light."

The Vatican will on Oct. 9 mark the 50th anniversary of Pius' death with a conference and photo exhibition.

Historians have been calling on the Vatican to open up all its archives on the period.

The Vatican says while some of the archives of the period are still closed for organizational reasons, most of the significant documentation regarding Pius is already open to scholars.

Last year, the Vatican's saint-making department voted in favor of a decree recognizing Pius's "heroic virtues," a major hurdle in a long process toward possible sainthood that began in 1967. But Pope Benedict has so far not approved the decree.

Some Jewish groups have said the Vatican should freeze the beatification process but others say it is an internal Church matter.