The Archbishop of Sydney has ordered a complete review of the archdiocese's professional standards and safeguarding policies after a royal commission heard further shocking accounts of sexual abuse at the hands of clergy.

Speaking of the shame and disillusionment felt by clergy and faithful after sex abuse accounts and allegations, Archbishop Anthony Fisher says he is determined to ensure it never happens again in the church.

"We may feel disillusioned, contaminated, ashamed," he said in a letter to Sydney Catholics on Monday.

"I am determined that we will do all we can to ensure such things never happen again in our church; that those entrusted with the care of the young and vulnerable `care for the lambs' and keep them safe; and that those already harmed are brought justice and compassion."

He said he would soon make announcements about further improvements to the Sydney Archdiocese professional standards and safeguarding practices, and he wanted the "best contemporary testing and discernment" for seminarians, as well as improved protocols and responses to allegations and the needs of survivors.

He goes on to warn there will be more to "lament and more humiliation and purification ahead for the Church".

The Royal Commission into Institutional Responses to Child Sexual Abuse is currently conducting hearings into abuse committed by clergy in Ballarat.

Last week's hearings reverberated to Rome, where former Sydney archbishop and now Vatican finance chief, Cardinal George Pell, rejected claims he was told about pedophile priests in the Ballarat diocese while he served there as a priest.

Archbishop Fisher defended his predecessor as the first church leader to introduce a contemporary process to confront abuse.

"Many things are being said about the Church at the moment, some of them fair, some of them not so fair," he said, before referring to accusations the church is engaged in self protective legal practices.

"Cardinal Pell was the first Church leader in Australia to introduce a more contemporary process to confront this evil and he repeatedly apologised when mistakes were made."

Commission chair Justice Peter McClellan has made it clear church figures, including Cardinal Pell, will have to answer serious allegations about what they knew about the abuse and when, and some may have findings made against them.