The state inquiry into mother and baby homes has confirmed 'significant quantities' of human remains at a site in Tuam, Co Galway.
The remains were found in what is believed to be a waste treatment structure at the former Bon Secours home, although the inquiry team has "not yet determined what the purpose" of the structure was.
The commission says remains were discovered in 17 out of 20 chambers in the septic tank-style structure.
The age-at-death of the remains is believed to be between 35 foetal weeks and 2-3 years.
Radiocarbon dating of the recovered samples suggest the remains "date from the timeframe relevant to the operation of the Mother and Baby Home".
The home in Tuam operated between 1925 and 1961, and the samples are likely to date from the 1950s.
In a statement, the Mother and Baby Home Commission of Investigation said: "The Commission is shocked by this discovery and is continuing its investigation into who was responsible for the disposal of human remains in this way.
"Meanwhile, the Commission has asked that the relevant State authorities take responsibility for the appropriate treatment of the remains. The Coroner has been informed."
"Very sad and disturbing news"
Children's Minister Katherine Zappone said: "This is very sad and disturbing news. It was not unexpected as there were claims about human remains over the years.
"Today is about remembering and respecting the dignity of the children who lived their short lives in this Home. We will honour their memory and make sure that we take the right actions now to treat their remains appropriately."
The commission is set continue its work under the established terms of reference - including matters such as post mortem practices and procedures.
The Government say Galway County Council will engage with the commission regarding the immediate next steps at the site.
An information line for factual information and a service for those who feel personally affected by the news will be established.
The dedicated telephone information line can be reached at 01-6473118 or 01-6473232.
Minister @KZapponeTD - Up to now we had rumours. Now we have confirmation that the remains are there. pic.twitter.com/NslLbe06lj
— MerrionStreet.ie (@merrionstreet) March 3, 2017
Anne Rabbitte, Fianna Fáil spokesperson on children and youth Affairs, called the discovery 'extremely sad and deeply worrying'.
She said: “This latest discovery is extremely distressing and will no doubt evoke painful memories for the women and children who spent time in Mother and Baby Homes.
"I want to commend the members of the Commission for the compassion with which they have undertaken their work, as well as paying tribute to the women who have come forward to share their stories."
Sinn Féin deputy leader Mary Lou McDonald said she was shocked by the discovery, and said all remains "should be recovered and given an appropriate and respectful burial".
"The truth should be set out"
Colm O'Gorman of Amnesty International Ireland, meanwhile, said: “Today’s distressing revelations underline the need to ensure that this Commission of Investigation is a meaningful opportunity to finally and fully ensure truth and accountability for what happened to women and children in these institutions.
"Our thoughts are very much with those most affected by today’s reports, the women who were former residents of the home and their loved ones," he added.
And Labour TD Joan Burton added: "These findings are truly gruesome and no doubt deeply upsetting to anyone associated with the Tuam home.
"The grim discovery also highlights the important work of local historian Catherine Corless in bringing this case to light.
“It now appears as though these children were interred in some kind of mass grave, possibly without normal funeral rights, and maybe even without their wider families having been made aware.
"It is now incumbent upon the Catholic Church to assist in whatever way they can, so that the truth should be set out in relation to these matters.”
