A geophysical survey of infant burial grounds is to begin today at the site of the former Sean Ross Abbey Mother and Baby Home in Tipperary.
The survey is expected to last a number of days. It is understood that the survey is being carried out on foot of information received by the Commission from a member of the public.
It is the first time that any potential infant burial site outside of Tuam has been examined and comes more than three years after the first geophysical survey of the Tuam site.
The plans were confirmed in the Commission's fourth interim report, which requested a 12-month extension to publish its final report. It will now report in February 2020 after the extension was granted by the Cabinet.
The Sisters of the Sacred Heart of Jesus and Mary, which ran the Sean Ross Abbey and Bessborough institutions, gave death registers it held for the homes to the HSE in 2011. They are now held by Tusla.
In the case of Sean Ross Abbey, the death register lists a total of 269 deaths between 1934 and 1967. However, research by campaigners indicates that hundreds more children may have died there.
The Commission states in the fourth interim report that it has had "difficulties" uncovering the burial arrangements at a number of institutions and that the drafters of its terms of reference "are unlikely to have foreseen the extent of the problem and the amount of time and effort that has had to be given to this issue"
It will now also deliver a substantial report on burial arrangements for persons who died while resident in these institutions by March 15.
The Commission has said it is "dismayed" that the HSE has discovered such little information in relation to the involvement of health boards with Mother and Baby Homes and said it was clear that the HSE "does not have any system, much less a proper system, of storing and archiving material".
The report reveals that the Commission has received more than 100,000 pages of documentation sought under discovery from the Department of Health and the Department of Children and Youth Affairs (DCYA), with thousands more pages being delivered just last month.
To date, it has spoken to 519 witnesses through the work of its Confidential Committee and expects this process to be completed by the end of this month.
Speaking after the Cabinet meeting, Children's Minister Katherine Zappone apologised to survivors upset at the delaying of the final report but said the additional time will ensure the Commission can fully complete its work.
In a statement, Adoption Rights Alliance said it hoped the request for an extension was a sign that the Commission was undertaking a thorough investigation but that this was impossible to know as it operates "in secret" and has refused requests for public hearings.
Paul Redmond of the Coalition of Mother and Baby Home Survivors hit out at the decision to grant an extension and said that the survivor community had been "utterly failed and stabbed in the back" by Minister Zappone and Taoiseach Leo Varadkar.
Founder of the Bethany Home Survivors Group Derek Leinster hit out at the granting of the extension and said survivors of the Protestant orphanages had waited long enough for redress.
"We have had enough talking and want action. The Residential Institutions Redress Board (RIRB), that can pay compensation, is still in operation. Refer us there or set up a fast forum to give overdue justice now," he said.