Sydney: Pope Benedict XVI apologised on Saturday to victims of child sex abuse by Roman Catholic clergy in Australia, describing their acts as "evil" and a grave betrayal of trust that has brought great shame on the church.

Benedict said during an address at a Mass in Sydney, "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.

"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 US.

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

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

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.