Pope Benedict XVI said he was "deeply sorry' for the sexual abuse of children by Australia's Catholic clergy, delivering a strongly-worded apology Saturday that described their acts as evil and a grave betrayal of trust.

"I would like to pause to acknowledge the shame which we have all felt as a result of the sexual abuse of minors by some clergy and religious in this country," Benedict said during an address at a Mass in Sydney.

"I am deeply sorry for the pain and suffering the victims have endured. I assure them as their pastor that I too share in their suffering," he said.

"Those responsible for these evils must be brought to justice."

Benedict has expressed regret before about the clergy abuse scandal that has rocked the church in recent years — notably during a visit to the United States in April when he also met privately with a small number of victims. But the language of Saturday's apology was stronger than the pope's comments in the United States.

There was no immediate word whether Benedict would meet with victims of clergy abuse during his Australia trip, which ends Monday.

Support groups for victims of church abuse in Australia, whose numbers are not known but who activists say are in the thousands, said a papal apology is not enough and demanded the church end what they say is a continuing cover-up of the scale of the problem and stop fighting compensation claims lodged in civil courts.

"Sorry is not enough. Victims want action, not just words," the Broken Rites group said in a statement posted Saturday on its Web site.

The pontiff is in Australia to lead hundreds of thousands of pilgrims in the church's World Youth Day, a global celebration meant to inspire a new generation of Catholics.

During his appearances in Australia, Benedict has spoken about the need to strengthen traditional Christian values including charity and chastity, and decried the selfishness and greed of today's "cult of material possessions."

In his remarks Saturday, the pope said the sexual abuse scandal had badly damaged the church.

"These misdeeds, which constitute so grave a betrayal of trust, deserve unequivocal condemnation," he said. "They have caused great pain, they have damaged the church's witness."

About 300 people protested Saturday for what they called the pope's antiquated and discriminatory views, holding a contest for the T-shirt that would most annoy Roman Catholics and chanting: "The pope is wrong, put a condom on!"

The boisterous protest at a square in the city's center included inflated condoms floating above the crowd and some participants dressed as nuns and priests. They listened to speeches by activists supporting sex education and safe sex practices at Taylor Square.

"It's good that people protest against the pope's homophobia and misogyny," Alex Bainbridge of the Socialist Alliance told the crowd. "We don't want a war against sex, we want a war against sexually transmitted infections. We're here for the people who could be saved if they had adequate sex education and access to condoms."

Police on horseback and on foot patrolled the site at Taylor Square, but there were no signs of trouble.

Benedict will join tens of thousands of young Catholics for a couple of hours later Saturday at an open-air vigil held at a horse race track in Sydney. He will lead a Mass on Sunday before a crowd estimated at more than 200,000 that will mark the culmination of the World Youth Day festival.

On Friday, Benedict told representatives of Islam and other faiths that they must unite to combat religion's role in "sinister and indiscriminate" violence.

Without mentioning terrorism directly, the pontiff said there were those who were using religion "as a cause of division rather than a force for unity." He was speaking in a 40-minute exchange with Australian Jewish, Muslim, Hindu and Buddhist leaders in Sydney.

"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.

The remarks come as the Vatican tries to cool lingering anger among Muslims over a speech Benedict gave in 2006 that appeared to associate Islam with violence. Benedict quickly apologized for the link.