Pope Benedict XVI has apologised for the sexual abuses committed by Roman Catholic clergy in Australia.

During a mass in Sydney on Saturday, the pope described the acts as "evil", a grave betrayal of trust and as bringing great shame on the Catholic church.

Victims say the issue has been covered up and apologies do not go far enough.

The pope is in Sydney for World Youth Day, a global celebration meant to inspire a new generation of Catholics.

However, his 10-day visit, which ends on Monday, has been overshadowed by the issue of child sex abuse.

'Misdeeds'

Speaking during a mass at St Mary's cathedral, the pope said: "I am deeply sorry for the pain and suffering the victims have endured.

"These misdeeds, which constitute so grave a betrayal of trust, deserve unequivocal condemnation.

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

There was no immediate confirmation of whether the pope would meet the victims of clergy abuse in person.

Support groups have criticised the speech. Campaigners estimate the number of victims to be in the thousands.

Broken Rites Australia, a group that supports victims of church sex abuse, said in a statement: "Sorry is not enough. Victims want action, not just words."

Broken Rites said the pope should apologise in person to individuals.

The pope will lead a mass on Sunday before an estimated crowd of more than 200,000 that will mark the culmination of the World Youth Day festival.

He has expressed regret before about the clergy abuse scandal that has rocked the church in recent years, notably during a visit to the US in April when he also met privately a small number of victims.