More than 500 cases of physical violence and 67 cases of sexual abuse have been revealed between 1945 and the early 90s.

Over five hundred members of the world-famous Regensburger Domspatzen (literally “cathedral sparrows”) boys choir in Germany, some as young as eight years old, were abused between 1945 and 1990, according to a new independent report by lawyer Ulrich Weber.

“Pre-school victims of the Regensburg Domspatzen in Etterzhausen and Pielenhofen described the institution as a prison, hell and a concentration camp,” Weber said at a press conference on Tuesday at which he presented his findings and was reported on by CNN. “Many of them called the time there as the worst of their lives, marked by violence, fear and helplessness.”

The renowned choir, which provides the music for St Peter’s Cathedral in Regensburg in Bavaria, appears on numerous recordings, has toured internationally, and performed concerts for the likes of Queen Elizabeth II and Popes John Paul II and Benedict XVI.

According to the report, boys who tried to escape the boarding school were beaten and humiliated in front of other choristers. Reasons for the abuse were “misconduct or poor performance of the students, but also arbitrariness by the educators” and violence was used daily, the report said.

The report found that 547 former pupils and choristers had probably been the victims of physical and/or sexual abuse. 500 students said they had been the victims of physical violence, while 67 said they had been the victims of sexual abuse, and some said they had experienced both. Weber was unable to contact or speak directly to a number of former students and estimates that the true number of victims may be as high as 700.

The 440-page report, which was commissioned by the Diocese of Regensburg in 2015, accuses 49 members of the Catholic Church of carrying out the abuse under a “culture of silence”, with nine members found to have been involved in sexual abuse. Weber said the alleged perpetrators were unlikely to face criminal charges because the crimes occurred too long ago.

Weber also criticised church figures for failing to act in preventing the abuses, singling out Georg Ratzinger – elder brother of former pope Benedict XVI – who lead the choir from 1964 to 1994. While Weber said that Ratzinger, who is now 93, had no knowledge of the sexual abuse – he has denied any knowledge of what went on – “one can accuse him of looking the other way and failing to intervene,” Weber said.

“The problem of sexual abuse that has now come to light was never discussed,” Ratzinger said in 2010 when reports of abuses at the institution first emerged. He admitted to slapping choirboys but said he now regretted using corporal punishment.

“Everyone knew about it,” a former pupil of the school, Franz Wittenbrink, told Spiegel magazine in 2010 according to a report in the UK’s Telegraph. “I find it inexplicable that Georg Ratzinger, who had been cathedral bandmaster since 1964, apparently knew nothing about it.”

“[Ratzinger] is and was a passionate musician, priest and educator and he’s an emotional person, who also slapped students, especially in the beginning. He also stated that in an interview and regrets it,” said Vicar General of Regensburg Diocese Michael Fuchs at the press conference on Tuesday. “He said multiple times that he wasn’t aware of sexual abuse, except for a case in 1958. He said he wrongly assessed the scale of these abuses that occurred in pre-school. He received hints over and over again but he didn’t pay enough attention to them. He apologised to the victims in an interview and I can’t see that he changed his view on this.”

The report said that the diocese has already made efforts to rectify “former organisational weakness” and that “the transparency and willingness to cooperate between the leaders of the Domspatzen and the bishopric in relation to this investigation is evaluated very positively.”

“We all made mistakes and have learned a lot,” Fuchs said. “We see today that we could have done things better and sooner.”

This new report comes in the wake of the report in Australia released by the Catholic Church earlier this year revealing that seven percent of priests working between 1950 and 2009 have been accused of child sex crimes – though not specifically with choirboys – with 4,444 alleged incidents recorded in the survey.