Historian Catherine Corless has turned down an invitation from the Taoiseach's office to attend a civic reception for Pope Francis.
She told Newstalk's Pat Kenny Show that she had decided "to stand with the babies" and would instead participate in a vigil with survivors of the Tuam Mother and Baby home in Galway.
Ms Corless carried out extensive research work which led to the discovery of a mass grave for infants on the site of the Bon Secours home.
When asked why she had turned down the invitation she said: “I did question them, would there be any chance of having a word with the Pope for the survivors of the Tuam home and the other Mother and Baby homes.
“They said no, that nobody would be talking to him.
“I just felt it was pointless then so I thanked them and said I was taking a stand with the babies who were buried in the sewage tank in Tuam.”
She said there would be a vigil held in Tuam on Sunday at the same time as the papal Mass.
Ms Corless also said the Church had done “absolutely nothing” to help get to the truth about what happened at the Tuam mother and baby home.
“We have asked the Taoiseach and other ministers to help us out,” she said.
“We have asked the Church to meet with survivors and to talk to us about the babies in the sewage tank. We have asked the Bon Secours sisters to give us some record, to come to Tuam, to help the survivors; to talk to them. For the last four years none of the priests or the Archbishop of Tuam indeed would entertain us.”
When she originally made the discovery in 2004 she thought she could hand over the investigation to the Church and the Government.
“They are just turning a blind eye to the fact that 796 young babies and young children are buried on that site and they are buried in a sewage area.
“In the last year and a half, they are still daddling and there is no response whatsoever from the Church.
“I just felt I had to take a stand with the babies on that day.”