THE HAGUE, Netherlands (AP) -- As many as 20,000 children endured sexual abuse at Dutch Catholic institutions over the past 65 years, and church officials failed to adequately address it or help the victims, according to a long-awaited investigative report.

The findings released Friday detailed some of the most widespread abuse yet linked to the Roman Catholic Church, which has been under fire for years over abuse allegations in Europe, the United States and elsewhere.

Based on a survey of 34,000 people, the report estimated that 1 in 10 Dutch children suffered some form of sexual abuse _ a figure that rose to 1 in 5 among children who spent part of their youth in an institution such as a boarding school or children's home, whether Catholic or not.

``Sexual abuse of minors,'' it said bluntly, ``occurs widely in Dutch society.''

The findings prompted the archbishop of Utrecht, Wim Eijk, to apologize to victims on behalf of the Dutch church, saying the report ``fills us with shame and sorrow.''

The abuse ranged from ``unwanted sexual advances'' to rape, and abusers numbered in the hundreds and included priests, brothers and lay people who worked in religious orders and congregations. The number of victims who suffered abuse in church institutions likely lies somewhere between 10,000 and 20,000, according to the probe, which went back as far as 1945.

The commission behind the investigation was set up last year by the Catholic Church under the leadership of a former government minister, Wim Deetman, a Protestant, who said there could be no doubt church leaders knew of the problem. ``The idea that people did not know there was a risk ... is untenable,'' he told a news conference.

Deetman said abuse continued in part because bishops and religious orders sometimes worked autonomously to deal with the abuse and ``did not hang out their dirty laundry.'' However, he said the commission concluded that ``it is wrong to talk of a culture of silence'' by the church as a whole.

Colm O'Gorman, executive director of Amnesty International in Ireland and a victim of clergy abuse, criticized the Dutch inquiry because it was established by the church itself.

``It is the Dutch government that should be putting in place a meaningful investigation,'' O'Gorman said.

Even so, he said the report ``highlights widespread abuse on a scale I think would be shocking to most Dutch people.''

But O'Gorman added that ``the scale of the abuse is in and of itself not the significant issue. It is whether it was covered up and, significantly, this report suggests it was.''

Nearly a third of the Netherlands' 16 million people identify themselves as Catholic, making it the largest religion in the country, according to the Dutch Central Bureau for Statistics for 2008.

The Dutch probe followed allegations of repeated incidents of abuse at one cloister that spread to claims from Catholic institutions across the country.

The investigating commission received some 1,800 complaints of abuse at Catholic schools, seminaries and orphanages. It then conducted the broader survey of 34,000 people for a more comprehensive analysis of the scale and nature of sexual abuse of minors in the church and elsewhere.

In one order, the Salesians of Don Bosco, the commission found evidence that ``sexually inappropriate behavior'' among members ``may perhaps have been part of the internal monastic culture.''

Bert Smeets, an abuse victim, said the report did not go far enough in investigating and outlining in precise detail exactly what happened.

``What was happening was sexual abuse, violence, spiritual terror, and that should have been investigated,'' Smeets told The Associated Press. ``It remains vague. All sorts of things happened, but nobody knows exactly what or by whom. This way they avoid responsibility.''

The commission said about 800 priests, brothers, pastors or lay people working for the church were identified in the complaints. About 105 of them are still alive, although it is not known if they remain in church positions. Their names were not released.

Prosecutors said in a statement that Deetman's inquiry had referred 11 cases to them _ without naming the alleged perpetrators. Prosecutors opened only one investigation, saying the other 10 did not have sufficient details and happened too long ago to prosecute.

The latest findings add to the growing evidence of widespread clergy abuse of children documented in the United States, Canada, Ireland, Belgium and other countries, forcing Pope Benedict XVI to apologize to victims whose trauma was often hidden by church cover-ups.

In September, abuse victims and human rights lawyers, upset that no high-ranking church officials have yet to be prosecuted, filed a complaint in the United States urging the International Criminal Court to investigate the pope and top Vatican officials for possible crimes against humanity. The Vatican called the move a ``ludicrous publicity stunt.''

An American advocacy group involved in that case, the Center for Constitutional Rights, called the Dutch findings ``yet another example of the widespread and systematic nature of the problem of child sex crimes in the Catholic Church.''

``If similar commissions were held in every country, we would undoubtedly be equally appalled by the rates of abuse,'' it said.

Archbishop Eijk said the victims in the Netherlands would be compensated by a commission the Dutch church set up last month and which has a scale starting at $6,500 ((euro) 5,000), rising to a maximum of $130,000 ((euro) 100,000) depending on the nature of the abuse.

O'Gorman criticized the church-established compensation scheme.

``It is simply not appropriate for the church to be the decider'' of compensation, he said. ``It is important the Dutch government recognizes its responsibility to ensure access to justice ... to all victims.''