The Government has been urged to expand the mother and baby home redress scheme as the current proposals simply "heap abuse upon abuse".
Campaigners say the scheme is "flawed" as it excludes 40% of survivors and denies healthcare to two-thirds.
The Department of Children has refused to release details of how the terms of the scheme were decided, claiming this information is "not in the public interest" and publishing it "may only serve to cause unnecessary distress to an already vulnerable group".
Under the proposals, children who spent less than six months in mother and baby homes will not qualify for redress. It also does not take into account those who were abused while boarded out.
Responding to an FOI request which sought the release of documents relating to the policy deliberations, the department said the payment scheme is long-awaited and is a particular focal point — and often flashpoint — for many with an interest in the broader topic.
"Premature release of policy deliberations into the public domain carries significant risk to policy decision-making processes, particularly in areas that are highly contentious."
In denying access to the information, the Department of Children added the Government was obliged to take account of a range of considerations in developing the redress scheme and "unfortunately some of these considerations may seem unpalatable or even cold" to survivors individually and their families in the context of their own unique and distressing experience.
Assistant principal officer Enda Gallagher said the Government and department officials must be given the opportunity to undertake "difficult discussions" within a process that allows for the release of information at an appropriate time.
"It is my view that this is not while the deliberative process is still very much ongoing and the bill is still being debated in the Houses," he said.
The redress legislation is expected to come before the Dáil on Wednesday night for a vote.
However, campaigners say Children's Minister Roderic O'Gorman has provided "no logical explanation" as to why the scheme excludes everyone separated from their mother before the age of six months in a mother and baby homes.
The scheme also excludes people who suffered abuse in adoptive or ‘boarding out’ placements despite repeated survivor testimony which the Commission of Investigation’s Confidential Committee described as a "stream of similar accounts of beatings and abuse of all kinds".
Meanwhile, Mr O'Gorman has appointed international human rights lawyer and barrister Caoilfhionn Gallagher as Special Rapporteur on Child Protection for a three-year term.
She will take over from Professor Conor O'Mahony, whose term of office as Special Rapporteur on Child Protection expired in July 2022.
Ms Gallagher, who also sits part-time as a coroner responsible for undertaking investigations into suspicious child deaths, said: “There are many pressing and urgent challenges, some of which have been highlighted by the UN Committee on the Rights of the Child in the days leading up to my appointment.
"This independent role is a vital one, and I look forward to working with the Government, specialist organisations and children and young people during my term to meet my mandate," she said.
Ms Gallagher was appointed as a national reviewer for the Child Safeguarding Review Panel for England and Wales from 2019 to 2021, a role requiring the investigation of systemic child protection issues and learning national lessons from child deaths and other cases involving serious harm to children.