The study, commissioned by the German Episcopal Conference, was to be officially presented on September 25, but several local media published key findings, including the damning finding that more than 3,600 children were sexually assaulted by priests in Germany for nearly seven decades.
The authors of the study also warned that the true scale of abuse may be greater since some documents were "destroyed or manipulated."
"We are aware of the extent of the sexual abuse the study has shown, we are shocked and ashamed," said Bishop Stephan Ackermann on behalf of the conference.
The aim of the study is to shed light on "this dark side of our Church, for the sake of those affected, but also for ourselves to see the mistakes and do everything possible to prevent them from repeating themselves".
"I insist that the study is a measure that we owe not only to the Church but, above all, to those affected."
The report gives another blow to the Church after child abuse was discovered around the world.
According to the study, 1,670 clerics in Germany committed some type of sexual assault against 3,677 minors between 1946 and 2014, Spiegel Online reported. The majority of the victims were children.
More than half were 13 years old or younger at the time of the abuse, the study concluded after examining 38,000 documents from 27 German dioceses.
The investigation also discovered impunity, with official documents manipulated or simply crushed.
Predatory priests were often transferred to another location, but information about their criminal history was not provided to the new site.
Only one in three (566 of the 1,670 defendants) was subjected to disciplinary hearings by the Church, and most escaped with minimal punishment, Die Zeit said weekly, citing the report as well.
Of these, 154 cases ended without penalty, while 103 were closed with a warning.
Only 38% of the accused were prosecuted by civil courts, in relation to complaints filed by the victims themselves or their families.
Meanwhile, Ackermann expressed frustration over the fact that the report leaked to the media before the Church itself had analyzed it.
The Church had planned to offer psychological help lines around the official date of publication of the report for those affected, he said.
Over the past decade, several German Catholic institutions have revealed cases of child sexual abuse, including a Jesuit elite school in Berlin that admitted systematic sexual abuse of students by two priests in the 1970s and 1980s.
Last year, a world-famous Catholic choir school in Germany, the Regensburger Domspatzen school, revealed that more than 500 children suffered sexual or physical abuse in what the victims have compared to "prison, hell or a concentration camp."
Pope Francis was also embroiled in the worldwide sexual abuse scandal after conservative US Archbishop Carlo Maria Vigano claimed last month that the pontiff had personally ignored accusations of abuse against US Cardinal Theodore McCarrick for five years.
So far, Francis has refused to respond to the allegations.