The Catholic Church in Ireland is facing fresh accusations of child abuse after a researcher found records for 796 young children allegedly buried in a mass grave beside a former orphanage for the children of unwed mothers.

The researcher, Catherine Corless, says her discovery of child death records at the Catholic nun-run home in Tuam, County Galway, suggests that the former septic tank filled with bones is the final resting place for most, if not all, of the children.

Church leaders in Galway, western Ireland, said they had no idea so many children who died at the orphanage had been buried there, and said they would support local efforts to mark the spot with a plaque listing all 796 children.

Archbishop of Dublin Diarmuid Martin said that “if a public or state inquiry is not established into outstanding issues of concern surrounding the mother-and-baby homes, then it is important that a social history project be undertaken to get an accurate picture of these homes in our country’s history," the Irish Times reported.

Irish leaders lamented the horrendous discovery and called for an urgent inquiry into the case. Ministers of three departments — education, justice and children — promised to take steps to investigate the matter.

County Galway death records showed that the children, mostly babies and toddlers, died often of sickness or disease in the orphanage during the 35 years it operated from 1926 to 1961. The building, which had previously been a workhouse for homeless adults, was torn down decades ago to make way for new houses.

A 1944 government inspection recorded evidence of malnutrition among some of the 271 children then living in the Tuam orphanage alongside 61 unwed mothers. The death records cite sicknesses, diseases, deformities and premature births as causes of death.

Elderly locals recalled that the children attended a local school — but were segregated from other pupils and routinely bullied — until they were adopted or placed, around age 7 or 8, into church-run industrial schools that featured unpaid labor and abuse. In keeping with Catholic teaching, such out-of-wedlock children were denied baptism and, if they died at such facilities, Christian burial.

It is well documented that throughout Ireland in the first half of the 20th century, church-run orphanages and workhouses often buried their dead in unmarked graves and unconsecrated ground, reflecting how unmarried mothers — derided as "fallen women" in the culture of the day — typically were ostracized by society and their own families.

Records indicate that the former Tuam workhouse's septic tank was converted specifically to serve as the body disposal site for the orphanage.

Tuam locals discovered the bone repository in 1975 as cement covering the buried tank was broken away. Before Corless' research this year, they believed the remains were mostly victims of the mid-19th century famine that decimated the population of western Ireland.

Respectful of the unmarked grave in their midst, residents long have kept the grass trimmed and built a small grotto with a statue of the Virgin Mary.

Archbishop of Tuam Michael Neary said he would meet leaders of the religious order that ran the orphanage, the Bon Secours Sisters, to organize fundraising for a plaque listing the 796 names and to hold a memorial service there.

Corless and other Tuam activists have organized a Children's Home Graveyard Committee that wants not just a lasting monument to the dead, but a state-funded investigation and excavation of the site.

The government has declined to comment. Ireland already has published four major investigations into child abuse and its cover-up in Catholic parishes and a network of children's industrial schools, the last of which closed in the 1990s.

Al Jazeera and The Associated Press