Ireland's Roman Catholic Church told the order of nuns who ran the former home where a mass grave of almost 800 children was found that it must co-operate with any inquiry into the discovery.
Ireland is considering an investigation into what the government called a "deeply disturbing" discovery of an unmarked graveyard at a former home run by the Bon Secours Sister where 796 children died between 1925 and 1961.
The Archbishop of Tuam said that while it did not have any involvement in the running of the home, his diocese was horrified and saddened to learn of the scale of the number of children buried at the Church-run home.
"I can only begin to imagine the huge emotional wrench which the mothers suffered in giving up their babies for adoption or by witnessing their death. The pain and brokenness which they endured is beyond our capacity to understand," Archbishop Michael Neary said in a statement.
"Regardless of the time lapse involved this is a matter of great public concern which ought to be acted upon urgently."
The Bon Secours order was not available for comment.
Ireland's once powerful Church has been rocked by a series of scandals over the abuse and neglect of children. Public records show that 796 children died in the county Galway "mother-and-baby home" before its closure, according to a local historian.
Researcher Catherine Corless said the bodies were buried in a sewage tank on the grounds and that some of the dead were as young as three-months-old.
The Catholic Church ran many of Ireland's social services in the 20th century, including mother-and-baby homes where tens of thousands of unwed pregnant women, including rape victims, were sent to give birth.
Unmarried mothers and their children were seen as a stain on Ireland's image as a devout Catholic nation. They were also a problem for some of the fathers, particularly powerful figures such as priests and wealthy, married men.
Like the Magdalene Laundries, where single women and girls were sent, the mother-and-baby homes were run by nuns but received state funding. They acted as adoption agencies and in that capacity were overseen by the state.
