DUBLIN — The Catholic Church in Ireland is facing fresh accusations of child neglect after a researcher found records for 796 young children believed to be buried in a mass grave beside a former orphanage for the children of unwed mothers.

The researcher, Catherine Corless, said her discovery of child death records at the Catholic nun-run home in Tuam, County Galway, suggests that a 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.

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. This would reflect an Ireland that, in the first half of the 20th century, had one of the worst infant mortality rates in Europe, with tuberculosis rife.

Elderly locals recalled that the children attended a local school – but were segregated from other pupils – 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 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” were ostracized.