The Pope has spoken of his pain and shame at the failure of church authorities to tackle the grave scandal of clerical abuse in Ireland.
On the first day of his historic Irish visit, the pontiff said people had a right to be outraged at the response of senior figures in the Catholic Church to the "repellent crimes" inflicted on young people.
In a speech at Dublin Castle, he also expressed hope that remaining obstacles to reconciliation in Northern Ireland could be overcome.
With the reverberations of a litany of church sex abuse scandals casting a shadow over the first papal visit to Ireland in almost 40 years, Francis confronted the issue in his address inside the castle's St Patrick's Hall.
"With regard to the most vulnerable, I cannot fail to acknowledge the grave scandal caused in Ireland by the abuse of young people by members of the church charged with responsibility for their protection and education," he said.
"The failure of ecclesiastical authorities - bishops, religious superiors, priests and others - adequately to address these repellent 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 pontiff's predecessor, Pope Benedict, has also addressed the issue.
"His frank and decisive intervention continues to serve as an incentive for the efforts of the church's leadership both to remedy past mistakes and to adopt stringent norms meant to ensure that they do not happen again," Francis added.
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He said the Church in Ireland had played a role in child welfare which could not be obscured.
"It is my hope that the gravity of the abuse scandals, which have cast light on the failings of many, will serve to emphasise the importance of the protection of minors and vulnerable adults on the part of society as a whole," he said.
"In this regard, all of us are aware of how urgent it is to provide our young people with wise guidance and sound values on their journey to maturity."
The Pope said he also wished to acknowledge women who in the past had "endured particularly difficult circumstances".
On Northern Ireland, he praised those who helped forged the historic Good Friday Agreement in 1998.
In an apparent reference to the political deadlock in Northern Ireland, which has seen the north without a properly functioning devolved government for 20 months,
Francis said: "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 speech came after a private meeting with Taoiseach Leo Varadkar, and later the Irish premier urged the Pope to "listen to the victims" in his own address at Dublin Castle.
Wounds are still open & there is much to be done to bring about justice &truth &healing for victims & survivors. Today I asked the Pope to use his office & influence to ensure this is done here in Ireland and across the World. Above all, I asked him to listen to victims. pic.twitter.com/YnnITpLapr— Leo Varadkar (@campaignforleo) August 25, 2018
Earlier, he met President Michael D Higgins at his official residence in Phoenix Park.
Hundreds of thousands of people are expected to welcome Francis during his whistle-stop tour of the capital city and Co Mayo over the weekend.