By Philip Pullella
ROME (Reuters) -The conflict in Gaza cast a shadow on Monday over a major conference on the Vatican and the Holocaust, with one participant calling the carnage the worst slaughter of civilian Jews in one day since then.
The conference was organised after the opening in 2020 of Vatican archives of the pontificate of Pius XII, which led to the discovery of a letter showing that he knew details about the Nazi attempt to exterminate Jews in the Holocaust as early as 1942.
Cardinal Pietro Parolin, the Vatican secretary of state, changed his prepared opening comments to mention the "terrible and despicable attack" against "Israeli brothers and sisters".
Parolin said: "Unfortunately, violence, terrorism, barbarism and extremism undermine the legitimate aspirations of Palestinians and Israelis."
Riccardo Di Segni, the chief rabbi of Rome, said: "My thoughts are more there than here."
Two speakers from Israel's Yad Vashem Holocaust Remembrance Center cancelled their appearances at the three-day conference, which is bringing together historians and theologians to address Jewish-Christian relations after the opening of the archives.
Professor Deborah E. Lipstadt, the U.S. Special Envoy to Monitor and Combat Anti-Semitism, and who won a landmark case in London against Holocaust denier David Irving in 1996, sat in the front row.
"It's the greatest number of Jews killed in one day since the Holocaust," she told Reuters during a break in the conference, saying the previous record of civilians killed was a bombing of a Jewish community centre in Buenos Aires that killed 85 and injured hundreds in 1994.
"They (the Hamas gunmen) yelled 'Jahud, Jahud', (Arabic for Jew). They didn't say 'Israeli'. The overt anti-Semitism that we hear from supporters is significant, mind boggling and just dumbfounding," she said.
Israel's Kan TV said the death toll from the Hamas attack had climbed to 800. Meanwhile, Israel pressed on with retaliatory strikes, which have killed more than 500 people since Saturday.
Parolin also mentioned displaced and wounded Palestinians, saying "our closeness and prayers also go to their families, and all civilians, totally innocent".
Pope Francis had on Sunday called for an end to attacks and violence in Israel and Gaza, saying "war is defeat" that would not solve any problems, but only bring further suffering to innocent people.
Israel's ambassador to the Vatican, Raphael Schutz, told Reuters on the sidelines of the conference: "I understand the Vatican wants peace. We all want peace. But I would like to hear stronger words about Israel's right to defend itself."
The conference was jointly organised by the Vatican, Yad Vashem, the U.S. State Department, the United States Holocaust Memorial Museum and a number of Jewish groups.
Supporters of Pius say he worked behind the scenes to help Jews and did not speak out in order to prevent worsening the situation for Catholics in Nazi-occupied Europe. His detractors say he lacked the courage to speak out on information he had despite pleas from Allied powers fighting Germany.
(Reporting by Philip Pullella; Editing by Alison Williams)