At least 547 young members of the Regensburger Domspatzen boys choir in Germany were subjected to physical and in some instances sexual abuse over a period of 60 years, a new report says.
Some 49 members of the Catholic Church are accused of carrying out the abuse between 1945 and the early 1990s, according to the report’s findings.
Victims said the experience was like “a prison, hell and a concentration camp”.
A 2016 report into the allegations said that 231 children had been abused.
The alleged physical abuse relates to children attending both the Regensburger Domspatzen’s pre-school and high school, according to the lawyer tasked with investigating the abuse, Ulrich Weber.
Representatives from the Regensburger Domspatzen boys choir have yet to officially respond to the report.
Presenting his findings on Tuesday, Mr Weber said the investigation had found 500 cases of physical abuse and 67 instances of sexual abuse over six decades.
Of the 49 church members who carried out the abuse under what was described as a “culture of silence”, nine were found to have been involved in sexual abuse, Mr Weber added.
He said the victims described their experiences at the boarding schools in southern Germany as “the worst time of their lives, characterised by fear, violence and hopelessness”.
As head of the choir from 1964 to 1994, Georg Ratzinger could be “blamed for looking the other way and failing to intervene,” Mr Weber said.
Mr Ratzinger, the 93-year-old elder brother of former Pope Benedict XVI, has denied any knowledge of the alleged abuse and said that it was “never discussed” while he ran the choir.
The church has previously offered to pay the Regensburger victims compensation of between €5,000 (£4,436; $5,776) and €20,000.
The 1000-year-old choir was initially rocked by allegations of widespread sexual abuse in 2010.
The Catholic Church has been hit with a number of scandals in recent years. In the 1990s, revelations emerged of widespread abuse in Ireland and at the turn of the century, more cases of abuse were revealed in more than a dozen countries.
The UN has accused the Vatican of “systematically” adopting policies allowing priests to sexually abuse thousands of children.
Since his election, Pope Francis has appeared to offer new hope to victims, with a call for action on sex abuse in the Church.