The Roman Catholic church in the Netherlands was shamed on Friday when a comprehensive investigation of sexual abuse of children by clergy over 40 years found one in five vulnerable children had been molested.

An 1,100-page report from a commission led by a former education minister and Christian Democrat leader said it could identify 800 Catholic clergy and other church employees guilty of sexually abusing children in the 40 years from 1945 and that more than 100 perpetrators were still alive.

Children in institutional care, regardless of religious affiliation, in the Netherlands were at substantial risk of being abused during the period, the molestation rate – 20% – being twice that of elsewhere. The investigation led by Wim Deetman concluded that several tens of thousands of children had suffered sexual molestation.

With the Catholic church embroiled in child abuse scandals from Ireland to Austria and lay Catholics mobilising against the Vatican for root-and-branch reform of canon law to end celibacy in the priesthood and facilitate female ordination, the Dutch report was the latest damning verdict of serial abuse accompanied by persistent cover-ups.

Klokk, an abuse victims' organisation in the Netherlands, said the disclosures by the Deetman inquiry went much further than it had expected and cast doubt on the Dutch church's alleged efforts to come clean. Deliberately echoing common postwar German denials of knowing about the Holocaust, a Dutch cardinal, Ads Simonis, last year insisted that the church hierarchy was not involved in any cover-up.

"We did not know anything," he declared in German. Deetman on Friday ridiculed such denials. "The policy was no washing of dirty linen in public," he told journalists. "To prevent scandals, nothing was done, abuse not acknowledged, there was no help, compensation or support for the victims," the report said. Deetman said his inquiry had found that tens of thousands of children had been abused by Catholic clergy.

Around 2,000 alleged victims have come forward in recent months to lodge claims and threaten court action. The Dutch church recently launched a compensation fund for victims and last week the church in Belgium did the same following a parallel scandal that reached to the very apex of the Catholic hierarchy and saw 475 victims coming forward to report their experiences to an independent inquiry. In the US, meanwhile, victims' associations have hired lawyers to try to take the Vatican to the international criminal court in The Hague for allegedly aiding and abetting systematic serial abuse by its clergy.

Given the popular disgust within the lay church at the extent of the revealed abuse, the cover-ups, and the perceived half-heartedness of the authorities' response, reform movements are proliferating across Austria, Germany, Ireland, Belgium and the Netherlands. A powerful "We Are the Church" movement in Austria has gained broad support, challenging the Vatican and raising schismatic potential. Earlier this month in Belgium, a new movement was founded by dissident priests, dubbed "Believers Speak Out", calling for the ordination of married men and women, the lifting of curbs on divorcees, and other reforms.

"The Belgian church is a disaster," said Father John Dekimpe when launching the new organisation. "If we don't do something, the exodus of those leaving the church will just never stop." While officially the church refuses to admit that priestly celibacy is in any way connected with priestly abuse, Deetman on Friday made the link. "We do not consider it impossible that a number of cases would not have happened if celibacy was voluntary," he said. His report said that compulsory celibacy in the priesthood made priests more likely to engage in "transgressive conduct".