The Pope has spent 90 minutes meeting Irish survivors of clerical abuse and mistreatment in Dublin.
The "polite and cordial" discussion focused on the plight of past residents of Catholic homes for mothers and babies and victims of forced and illegal adoption.
The meeting took place at the Papal Nuncio's residence. The Papal Nuncio is the Pope's diplomatic representative to the Republic.
Fr Patrick McCafferty, the Belfast priest who was among the survivors of abuse who met with @Pontifex today, tells @irish_news that “It was a truly excellent meeting in every way.” #wmof2018 #popeinireland— William Scholes (@ScholesWilliam) August 25, 2018
A letter from survivors released afterwards said: "Around 100,000 single mothers who were forcibly separated from their babies were regularly told it was a mortal sin to search for, or even contact, their own sons and daughters.
"As an act of healing, Pope Francis, we ask that you make it clear to the now elderly and dying community of natural mothers and adoptees that there is no sin in reunion and rather that it is a joyous event that should be encouraged and facilitated by the Catholic Church."
They said many natural mothers and adoptees will be in attendance at a papal Mass on Sunday.
The letter added: "Five orders and congregations of Catholic nuns ran Ireland's notorious Mother and Baby homes where over 6,000 babies and children died as well as dozens of young mothers.
- Pope Francis warns Croke Park crowd of social media dangers
- Anti-clerical abuse protests held during Pope's visit
- Pope thrills Dublin crowds during Popemobile tour
- Leo Varadkar urges Pope to listen to abuse victims
- Pope Francis prays for Irish victims of abuse
- Pope Francis 'pained and shamed' by Church's clerical abuse failure?
- Belfast couple 'asked Pope to pray for peace in the north'
- Michael D Higgins tells Pope of anger felt by clerical abuse victims
- Pope Francis begins Irish visit
"These nuns have never taken responsibility for their wilful neglect. We ask you, Pope Francis, to publicly call on these nuns to acknowledge their actions and issue an unqualified apology to all the survivors of their institutions.
"We also request that you call on these nuns to immediately commit to paying the full cost of the current inquiry and any redress that may be awarded in the future."
The papal visit to Ireland has so far been dominated by the Vatican's response to clerical abuse.
Pope Francis met early Saturday evening for an hour and half with eight Irish survivors of clerical, religious and institutional abuse. Those present included Marie Collins and Fr Patrick McCafferty. #popeinireland— William Scholes (@ScholesWilliam) August 25, 2018
Clodagh Malone, who was born in Saint Patrick's Mother and Baby home in Dublin and adopted at 10 weeks old, asked the Pope to publicly state that the natural mothers who lost their babies to adoption had done nothing wrong, and call for reconciliation and reunion for these families broken by the Catholic Church both in Ireland and around the world.
The Pope agreed to include the message in his Mass on Sunday, survivors said.
Paul Redmond, who was born in Castlepollard Mother and Baby home in Co Westmeath and adopted at 17 days, asked the Pope to publicly call upon the orders of nuns who ran the homes to immediately accept their responsibilities for the "horror" that went on for generations in the homes, issue an unqualified and sincere apology, and pay the full costs of inquiries and redress in Ireland as a matter of urgency.
The Pope did apologise to all for what happened in the homes, the survivors said.
Their statement added: "Pope Francis condemned corruption and cover up within the church as 'caca'.
"Literally filth as one sees in a toilet, his translator clarified."
Mr Redmond said they hope there will be more movement from the church on the issue of Mother and Baby homes.
"The Pope was genuinely shocked to hear about the 6,000 babies who died and the 3,000 banished babies... lifted his hands to his head in shock."
Ms Malone said it was a powerful meeting.
"He listened with a genuine interest, and he asked many questions about Mother and Baby homes."