547 pupils at one of Germany’s most famous Roman Catholic choir schools were physically or sexually abused between 1945 and 2015, an independent report has found, with some boys likening the institution to “prison, hell or a concentration camp”, according to The Guardian.

The 440-page report chronicles teachers at the school in Regensburg doling out physical violence including slapping boys in the face so hard the marks could be seen the next day, whipping them with wooden sticks and violin bows and subjecting them to severe beatings.

Boys who tried to escape the Regensburger Domspatzen choir were hauled back to the school and beaten and humiliated in front of other boys, it said.

Allegations of abuse at the institution, which traces its history back 1,000 years and tours the world to perform choral music, surfaced in 2010.

After criticism of the ensuing investigation, the diocese, which acknowledged on Tuesday it had “made mistakes”, commissioned the lawyer Ulrich Weber in 2015 to put together the independent report.

Georg Ratzinger, 93, brother of the former pope Benedict XVI, led the choir from 1964 to 1994. He acknowledged in 2010 that he had slapped pupils in the face but said he had not realised how brutal the discipline was.

Weber said he was “to be blamed especially for turning a blind eye and not intervening despite having knowledge”, adding the investigation did not show he was aware of sexual abuse. Several testimonies said he was generally friendly.

It was not possible to contact Ratzinger for a comment.

Weber said the system was focused on achieving musical excellence and choral success and to that end a high degree of discipline was commonplace, providing a basis for violence.

He found that 547 former pupils had probably been victims of physical and/or sexual violence. Of those, 67 suffered sexual abuse. He blamed 49 individuals, 45 of whom were physically violent and nine of whom were believed to have committed sexual violence.

“Victims ... described the institution as a prison, hell and a concentration camp,” Weber told a news conference. “Many of them called the time there as the worst of their lives, which was marked by violence, fear and helplessness.”

Allegations of sexual and physical abuse at Catholic schools in Germany, in particular in the former pope’s native Bavaria, have shaken the church. Abuse scandals have also rocked it in the US, Austria and Ireland.

Choir school victims, many of whom implored their parents to let them come home, said they were still traumatised.