Pope Benedict XVI told Jewish leaders Thursday that Holocaust denial is "intolerable," especially if it comes from members of the clergy.
"The hatred and contempt for men, women and children that was manifested in the Shoah [Holocaust] was a crime against humanity," the Pope told 60 Jewish-American leaders in the Vatican.
"This should be clear to everyone, especially to those standing in the tradition of the Holy Scriptures ..." Reuters quoted him as saying.
The Pope also told the leaders he is preparing to visit Israel.
Thursday's meeting marks the first face-to-face talks with Jewish leaders since the Pope revoked the excommunication of Bishop Richard Williamson, who has denied the full extent of the Holocaust.
Days before his rehabilitation was made public, Williamson was shown on Swedish state television saying historical evidence "is hugely against six million Jews having been deliberately gassed" during the Second World War.
The Pope's move to reinstate the bishop provoked widespread condemnation. The Pope has said he was unaware of Williamson's views when he decided to lift the excommunication.
Speaking Thursday, the Pope said "any denial or minimization of this terrible crime [the Holocaust] is intolerable," particularly coming from a priest.
Pope calls on Williamson to recant his comments
The Pope's remarks were his strongest condemning the Holocaust denial.
German Chancellor Angela Merkel issued a statement last week calling on the Pope to make a clearer rejection of Holocaust denials. The Pope has demanded Williamson recant his comments before being fully readmitted into the Catholic Church.
Williamson has apologized to the Pope for the controversy he caused, but has yet to fully repudiate his comments. German magazine Der Spiegel reported Saturday that Williamson said he would re-examine research upon which he made his conclusions about the Holocaust.
Earlier this week, the conservative Society of St. Pius X has dismissed Bishop Richard Williamson as director of a seminary in Argentina.
Williamson and three other bishops were excommunicated in 1988 after they were consecrated by the late ultraconservative Archbishop Marcel Lefebvre without papal consent. In 1969, Lefebvre founded the traditionalist Society of St. Pius X, which was opposed to the liberalizing reforms of the Second Vatican Council, including its outreach to Jews.