Taoiseach Micheál Martin will make a State apology to the survivors of mother-and-baby homes in the Dáil next week, a spokesman for the Government has confirmed.
On Tuesday morning, the Cabinet will meet to approve a report by the Commission of Investigation into the homes.
The report will contain an estimate that 9,000 children died in 18 institutions between 1922 and the closure of the last such home in 1998.
The report will focus on 14 mother-and-baby homes and four county homes.
Sources have confirmed the estimate is based on infant mortality being twice as high for children born in the homes, compared to children in society at large.
Details of the publication were reported in the Sunday Independent.
Minister for Children Roderic O'Gorman will brief survivors of the mother-and-baby homes about the contents of the report in advance of publication.
A counselling service will also be made available to survivors when the report is released.
The Taoiseach is due to make his apology in the Dáil on Wednesday when it reconvenes after the Christmas break.
Tuam historian Catherine Corless has welcomed plans for the apology.
But she said the publication of the report must be followed by other actions, to show that concerns of survivors were being taken seriously.
"All the words in the world won't matter, unless there is action behind them," she added.
Ms Corless said she did not want to comment on speculation about the commission's findings, until the report was published on Tuesday.
However, she was pleased that the Taoiseach planned to make an apology to those impacted by the investigation.
And she reiterated a call from survivors for a formal apology by the Catholic Church and the religious orders that operated a number of homes around the country.
Ms Corless said this is what survivors have been waiting for and what they need, to allow for healing to take place.
Meanwhile, Minister O'Gorman said he was "deeply angered" to see details of the report leaked to a newspaper this morning.
In an email to survivors of mother and baby homes, Mr O'Gorman said it was always his intention that survivors should be the first to hear of the main conclusions of the commission's report, and the actions the Government plans to take on foot of it.
He said his department has worked hard to maintain the confidentiality of the report prior to publication, and to arrange for the first public airing of its contents to be with survivors in the online forum being hosted by the Taoiseach and himself on Tuesday, following the Cabinet meeting.
"I was deeply angered to see details of the report leaked in a newspaper this morning. I am very sorry that many of you have found out elements of the report in this way. It is not acceptable."
The minister said his department will be engaging colleagues across Government to ensure that no further information becomes public until the official publication on Tuesday.
In a statement this afternoon, a Government spokesperson said the Taoiseach had committed to a State apology, which was something that had been discussed and called for over many months.
"The Minister for Children and Taoiseach promised the government would not be found wanting after this report was published," the statement added.
"We understand the Minister of Children's concerns and we will discuss these further at a government level.
"It is important, as we have previously stated, that we respond to the needs of survivors with a comprehensive suite of measures upon publication of the report," it concluded.
Leaking of report 'unacceptable'
Leader of Sinn Féin Mary Lou McDonald said it is "absolutely not right that this Commission report was leaked".
Speaking to RTÉ's This Week, she said: "It has been five years in the making, this process for survivors and families has been really, really difficult and it will make for very difficult reading.
"Those whose lives were marked and marred by this experience know the full extent of the horror of what they want through.
Leaking from the Mother and Baby Homes Commissions of Investigation Report is shameful. A very bad start to what will be a number of very difficult days for survivors and their families. #motherandbabyhomes— Mary Lou McDonald (@MaryLouMcDonald) January 10, 2021
"It is not just grossly insensitive, it is unacceptable that any part of this report was leaked in advance of family and survivors having access to the report.
"I would hope that the minister will commit to establishing how the leak happened. The victims should have access to it a couple of days in advance of the rest of us."
Ms McDonald added the "apology is long overdue and necessary and forms of redress also need to be acted on".
Solidarity-People Before Profit TD Richard Boyd Barrett said that the details of the report being leaked in advance of its publication are shocking and that it is a "mishandling of sensitive issues".
He also said it is a breach of a promise to survivors that they would be the first to be consulted about the details of the report.
Speaking to the same programme, Mr Boyd Barrett said: "This latest leaking does not bode well for the seriousness and commitment of the government to give justice to the survivors.
"There should be an absolutely thorough investigation as to how on earth this information was leaked."
He said the survivors of these homes have still not had the commitments made to them fulfilled.
In a statement, Social Democrats spokesperson for Children Jennifer Whitmore said it is "extremely disappointing that the leak has occurred".
She said Mr O'Gorman "needs to set out how he will establish how the leak occurred".
Ms Whitmore added that "survivors must come first" and their needs and the assurances given to them "must be to the forefront as we await the release of the report".
Additional reporting Ailbhe Conneely