Pope Benedict has apologised for the sexual abuse of children by some Catholic priests in Australia.
Speaking at a mass in Sydney, the pontiff said those responsible for the abuse should be brought to justice.
'I am deeply sorry for the pain and suffering the victims have endured,' he said in a homily.
'These misdeeds, which constitute so grave a betrayal of trust, deserve unequivocal condemnation.'
'Those responsible for these evils must be brought to justice,' Pope Benedict said.
However, victims' support group Broken Rites said the apology was inadequate.
They said the Pope must not just apologise for past church abuses, but that he should implement a system of investigating abuse claims, where those involved are held accountable.
The organisation, which represents abuse victims in Australia, has a list of 107 convictions for church abuse, but says there could be thousands of victims.
Conga lines of teenagers grooved to pop music and nuns in black habits skipped between ranks of pilgrims in sleeping bags as a candlelight vigil with the Pope began in Sydney.
A crowd estimated at 200,000 crammed the city's 90-hectare (222-acre) Randwick racecourse for the vigil, with numbers expected to swell to 500,000 on Sunday as World Youth Day climaxes with a papal mass.
Irish girl Aisling O'Rourke was one of those who read at the mass.
