SYDNEY, Australia -- Pope Benedict XVI said today that he is deeply sorry for the pain and suffering caused to victims of clergy sex abuse.

The pope addressed a Mass attended by Australia's Roman Catholic bishops and seminarians. He said he wanted to acknowledge the "shame that we have all felt as result of the sexual abuse of minors by some clergy and religious" in Australia.

He said the deeds of clergy responsible for abuse were a grave betrayal of trust that had caused great pain, had damaged the Roman Catholic church, and deserved unequivocal condemnation.

Support groups for victims of church abuse in Australia, whose numbers are not known but who activists say are in the thousands, have demanded the pope make a full and open apology for clergy abuse and do more to prevent future abuse.

The pope was in Australia to take part in festivities for World Youth Day. Yesterday, he held an exchange with Australian Jewish, Muslim, Hindu and Buddhist leaders in Sydney. He told the representatives that they must unite to combat religion's role in "sinister and indiscriminate" violence.

"In a world threatened by sinister and indiscriminate forms of violence, the unified voice of religious people urges nations and communities to resolve conflicts through peaceful means and with full regard for human dignity," Benedict told the leaders, gathered in the gothic surrounds of Australia's largest Roman Catholic cathedral.

In reply, the delegates from the other creeds yesterday welcomed the pope's inclusionary stance, though Sheikh Mohamadu Saleem of the National Imams Council of Australia noted that discrimination between faiths was still a problem.

The meetings were part of a busy schedule for the 81-year-old pontiff at the festival, which organizers say has attracted more than 200,000 young Catholics to Australia's largest city. Halfway into his four-day official program, the pope looked fit and energetic.

Tomorrow, he will lead a Mass culminating the festival.