Some 216,000 children - mostly boys - have been sexually abused by clergy in the French Catholic Church since 1950, a damning new inquiry has found.
The head of the inquiry said there were at least 2,900-3,200 abusers, and accused the Church of showing a "cruel indifference towards the victims".
Pope Francis "felt pain" on hearing about the inquiry's finding, a Vatican statement said.
One of those abused said it was time the Church reassessed its actions.
François Devaux, who is also the founder of the victims' association La Parole Libérée (Freed speech), said there had been a "betrayal of trust, betrayal of morale, betrayal of children".
The inquiry found the number of children abused in France could rise to 330,000, when taking into account abuses committed by lay members of the Church, such as teachers at Catholic schools.
For Mr Devaux it marked a turning point in France's history: "You have finally given institutional recognition to victims of all the Church's responsibility - something that bishops and the Pope have not yet been prepared to do."
According to the Vatican statement, the Pope learnt about the report after he met visiting French bishops in the last few days.
"His first thoughts are for the victims, with a deep sadness for their wounds and gratitude for their courage in coming forward," it read.
"His thoughts also turn to the Church in France, and that, in recognising these terrible events and united by the suffering of the Lord for his most vulnerable children, it can take the path of redemption."
The report's release follows a number of abuse claims and prosecutions against Catholic Church officials worldwide.
The independent inquiry was commissioned by the French Catholic Church in 2018. It spent more than two-and-a-half years combing through court, police and Church records and speaking to victims and witnesses.
Most cases assessed by the inquiry are thought to be too old to prosecute under French law.
'Victims were not believed'
The report, which is nearly 2,500 pages long, said the "vast majority" of victims were boys, many of them aged between 10 and 13.
It said the Church had not only failed to prevent abuse but had also failed to report it, at times knowingly putting children in contact with predators.
"There was a whole bunch of negligence, of deficiency, of silence, an institutional cover-up," the head of the inquiry, Jean-Marc Sauvé, told reporters on Tuesday.
He said that until the early 2000s, the Church had shown "deep, total and even cruel indifference" towards victims.
"The victims are not believed, are not listened to. When they are listened to, they are considered to have perhaps contributed to what they had happen to them," he explained.
He added that sexual abuse within the Catholic Church continued to be a problem.
While the commission found evidence of as many as 3,200 abusers - out of a total of 115,000 priests and other clerics - it said this was probably an underestimation.
"The Catholic Church is, after the circle of family and friends, the environment that has the highest prevalence of sexual violence," the report said.
Olivier Savignac, head of victims association Parler et Revivre (Speak out and Live again), was abused at the age of 13 by the director of a Catholic holiday camp in the south of France.
He told the Associated Press news agency that before the abuse, he had thought of the priest as "someone who was good, a caring person who would not harm me".
"We keep this, it's like a growing cyst, it's like gangrene inside the victim's body and the victim's psyche," he said.
The inquiry found that about 60% of the men and women who were abused had gone on to "encounter major problems in their emotional or sexual lives".
This was over 70 years and more than half the cases were before 1970. But still - for many French this will be the moment they wake up to the sheer scale of the phenomenon of Church sexual abuse. What was once anecdotal and prurient is suddenly a defining feature of society.
The burden of the report is that ad-hoc expressions of repentance and a bit of tinkering with ecclesiastical structures are no longer good enough.
There has to be recognition that sexual abuse of youngsters by priests was systematic. It was the Church - not rogue individuals - that was responsible.
Many in the Church will be horrified by what they discover. Many will welcome the moment as a catharsis. As Sister Veronique Margron, president of the Conference of Religious Orders, put it: "If the Church must tremble, well let it tremble."
Calls for compensation
Only a handful of the cases covered by the inquiry had prompted any disciplinary action, let alone criminal prosecutions.
But while most cases are now too old to prosecute via the courts, the inquiry called on the Church to take responsibility for what happened, including by providing compensation to the victims.
It noted that while financial compensation would not address the trauma that victims had endured, it was "nonetheless indispensable as it completes the recognition process".
It also made a series of recommendations about how to prevent abuse, including training priests and other clerics, and fostering policies to recognise victims.
"We expect clear and concrete responses by the Church," a group of six victims' associations said.
The president of the Bishops' Conference of France, who co-requested the report, said the numbers of victims and their experiences were "beyond what we could imagine".
"I express my shame, my fear, my determination to act with them [the victims] so that the refusal to see, the refusal to hear, the desire to hide or mask the facts, the reluctance to denounce them publicly, disappears," Archbishop Eric de Moulins-Beaufort said.
The French Church has previously announced a plan for "financial contributions" to victims, beginning next year.
Earlier this year, Pope Francis changed the Roman Catholic Church's laws to explicitly criminalise sexual abuse, in the biggest overhaul of the criminal code for nearly 40 years.