At least 547 children of Germany’s most famous Roman Catholic choir for boys were physically or sexually abused between 1945 and 1992, according to a report released on Tuesday, The Washington Post reported.

The 440-page report, released by lawyer Ulrich Weber, who was tasked with carrying out an independent investigation, shows the abuse was carried out by priests and teachers at the Domspatzen choir in Regensburg.

News reports said many boys likened the institution to a “prison, hell or a concentration camp”.

Forty-nine teachers at the school in Regensburg often slapped or whipped the boys with wooden sticks and violin bows, The Guardian reported. Those who tried to escape were brought back and then humiliated in front of the other children, it said.

Weber’s report said most of the abuse was concentrated in the 1960s and 1970s, when Pope Benedict XVI’s brother Georg Ratzinger was in charge, according to The Washington Post. This led Weber to assume that Ratzinger was aware of the sexual abuse, the report said.

Ratzinger, however, denied this in 2010, when the allegations against the Roman Catholic clergy in Germany first emerged. He had said, “Pupils told me on concert trips about what went on, but it didn’t dawn on me from their stories that I should do something…I ask the victims for forgiveness,” The Washington Post reported.

In 2010, following pressure from many victims, the diocese had called on Weber to conduct an independent inquiry into the alleged abuse.