Pope Benedict waves goodbye at the conclusion of the evening vigil during World Youth Day in Sydney, Australia, on Saturday. (Rob Griffith/Associated Press)

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.

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 which activists say are in the thousands, said a papal apology is not enough. They demanded the church end what they say is a continuing coverup of the scale of the problem and stop fighting compensation claims 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 website.

Inspiring a new generation of Catholics

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."

Benedict will join tens of thousands of young Catholics for a couple of hours later Saturday at an open-air vigil 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.