Pope Francis is to study a report into the Tuam Mother and Baby Home given to him on his Irish visit.
The two day trip was dominated by the issue of clerical sex abuse - with the Pontiff calling on the Irish people to forgive those in the church who covered it up.
Children's Minister Katherine Zappone was one of the first to meet the Pope when he arrived in Ireland on Saturday, highlighting the controversy of the Mother and Baby Home in Tuam.
The Pope told reporters on the papal flight to Rome on Sunday that Ms Zappone told him about the discovery of mass graves of children, and that the church has something to do with it.
He confirmed he has been sent a memo on the issue – but had yet to study it.
On Sunday the Pontiff acknowledged that senior members of the church kept quiet about child sexual abuse - calling on those at the mass in the Phoenix Park to forgive them.
During his 36 hour trip, the 81-year-old also meet with survivors of abuse, visited the Capuchin day centre for the homeless along with a brief visit to Knock Shrine where an estimated 45,000 people came out to see him.
People hold up names of children as they gather to protest at the site of the former Tuam home for unmarried mothers in Co Galway, where a mass grave of around 800 babies was uncovered | Image: Niall Carson/PA Wire/PA Images
"A conspiracy of silence"
As the he ended his visit, Archbishop Carlo Maria Vigano called on him to quit over his response to the global scandal.
Archbishop Vigano has said he warned Francis about allegations against American Cardinal Theodore McCarrick shortly after he became Pope in 2013.
The 88-year-old resigned last month over claims of sexual abuse against a 16-year-old boy.
Francis accepted McCarrick's resignation as cardinal last month, after a US church investigation found that an accusation he had sexually abused a minor was credible.
In an 11-page statement, the archbishop compared cover-ups of abuse within the church to "a conspiracy of silence not so dissimilar from the one that prevails in the Mafia".
"Pope Francis has repeatedly asked for total transparency in the Church," Archbishop Vigano, a frequent critic of the Pope, wrote in the letter, which was carried by the National Catholic Register and several other conservative media outlets in the US and Italy.
"In this extremely dramatic moment for the universal Church, he must acknowledge his mistakes and, in keeping with the proclaimed principle of zero tolerance, Pope Francis must be the first to set a good example for cardinals and bishops who covered up McCarrick's abuses and resign along with all of them," he said.
The Vatican has not commented on the accusations, which include an assertion that other top officials were warned about McCarrick - one of the highest-ranking figures within the Church - as early as 2006.
Archbishop Vigano - the papal envoy in Washington from 2011 to 2016 - timed the release of the bombshell letter to coincide with the second day of the World Meeting of Families.
With reporting from Paul Quinn in Rome
