Pope says 'outrage' justified over Irish Church abuse

However, he did not specifically mention the current scandal raging over a US grand jury report documenting at least 1,000 cases of clerical pedophilia.

"The failure of ecclesiastical authorities -- bishops, religious superiors, priests and others -- adequately to address these appalling crimes has rightly given rise to outrage, and remains a source of pain and shame for the Catholic community. I myself share those sentiments," the Pope said.

He was speaking to a hall in Dublin Castle packed with hundreds of political and religious dignitaries along with foreign diplomats.

Ireland's Prime Minister Leo Varadkar, who spoke before the Pope, did not skirt the current abuse revelations that have emerged in Pennsylvania.

"In recent weeks, we have all listened to heart-breaking stories from Pennsylvania of brutal crimes perpetrated by people within the Catholic Church, and then obscured to protect the institution at the expense of innocent victims," he said. "It is a story all too tragically familiar here in Ireland."

Varadkar called for "zero tolerance" of Church sexual abuse and asked the Pope "to adopt stringent norms meant to ensure that they do not happen again."

"Holy Father, I ask that you use your office and influence to ensure this is done here in Ireland and across the world," Varadkar said, and urged the Pope to listen to the victims.

The Pope is expected to meet later with some of the Irish victims of clerical sexual predators.

It is the first Papal visit to Ireland in 39 years, a country that has undergone seismic social changes in that time, with the introduction of divorce, gay marriage and more recently the legalization of abortion. In March 2010, Francis' predecessor, Pope Benedict XVI wrote a pastoral letter of apology for all of the abuse that had been carried out by Catholic clergy in Ireland.

In his speech, the Pope also paid tribute to the Good Friday Agreement that brought peace to Northern Ireland, which some fear could be threatened by the UK's decision to leave the European Union.

"We can give thanks for the two decades of peace that followed this historic agreement, while expressing firm hope that the peace process will overcome every remaining obstacle and help give birth to a future of harmony, reconciliation and mutual trust."

The Argentinian Pope remains highly popular in Ireland, and tens of thousands of people are expected at Dublin's Croke Park stadium Saturday evening for a concert-style event.

Hundreds of thousands more will attend a Mass celebrated by the Pope at the city's Phoenix Park on Sunday afternoon, with all 500,000 tickets for the free event booked out.

However, Pope Francis is also expected to face unprecedented protests over the clerical abuse scandals and the Church's handling of them. One protest, dubbed "Stand for Truth," will take place at the Garden of Remembrance in Dublin's Parnell Square at the same time as the Mass is celebrated.

Some protesters also say they have booked tickets to the event in Phoenix Park but will deliberately not use them as a form of silent protest against the Catholic Church and its actions. Organizers of the "Say Nope to the Pope" protest said on Facebook they hoped to show solidarity to abuse victims and "show the Church they don't have the control they used to."

On Tuesday the grand jury in Pennsylvania issued a report that 300 Catholic priests across the US state sexually abused children over seven decades, protected by church leaders.

The investigation, one of the broadest inquiries into church sex abuse in American history, identified 1,000 child victims, but said there were likely thousands more.

"Priests were raping little boys and girls, and the men of God who were responsible for them not only did nothing; they hid it all," the grand jury wrote.

On Sunday morning, the Pope will make a pilgrimage to the Shrine of Our Lady of Knock in County Mayo, more than 100 miles west of Dublin, where he will lead prayers for families around the world. All 45,000 tickets for this event are also booked out.

The last papal visit to Ireland was by Pope John Paul II in September 1979. More than a million people gathered for the papal Mass in Phoenix Park on that occasion, according to the Irish Times, representing about a third of the country's population at the time.

'We abandoned them'

On Monday, Francis acknowledged "with shame and repentance" the Catholic Church's failure to act over clerical abuse. In an unusually blunt letter, he wrote: "We showed no care for the little ones; we abandoned them."

The letter directly referred to the Pennsylvania report, which "detailed the experiences of at least 1,000 survivors, victims of sexual abuse, the abuse of power and of conscience at the hands of priests over a period of approximately 70 years," the Pope wrote.

Meanwhile, memories of Ireland's own abuse scandal are still vivid. And survivors have been critical of Francis' response so far.

Colm O'Gorman, an abuse survivor who is now executive director of Amnesty International Ireland, is behind the Stand for Truth protest.

He told CNN that the Vatican's announcement this week had created a "soap opera" in Ireland, with members of the media repeatedly calling survivors to ask whether they had been granted an audience with the pontiff.

Clerical abuse survivor Marie Collins, who resigned last year from a special Vatican commission created by Pope Francis to tackle child abuse, saying that senior clerics in the Church refused to implement their suggested safety policies, said she wanted to see action, not words.

"What I would like to see when the Pope comes to Ireland, is to come out, not make these sort of 'we're sorry,' type of statements, but to tell us what is he going to do -- and do it," Collins, who was assaulted by a priest when she was 13, told CNN.

"And it must be something concrete."