There could have been as many as 15,000 illegal adoptions in Ireland, according to Barnardo’s.
The charity’s claim comes shortly after the shocking announcement that there were 126 cases of incorrectly registered births in Ireland between 1946 and 1969.
Young mothers that had children outside of marriage were frequently sent to live at Catholic Church institutions, with many of them having their babies taken from them and sold to families in America.
Many mothers tried to trace their babies years later, only to be told they had died.
Fergus Finlay, Chief Executive of Barnardos in Ireland, said: “This was a crime against these people and their mothers. Mothers who were told that their babies had died.
Irish Minister for Children and Youth Affairs Katherine Zappone recently revealed that there were 126 confirmed cases of babies being registered incorrectly. These people will now be aged in their 40s, 50s, 60s and 70s. Tusla are attempting to contact them to inform them of the situation.
However, Barnardos believe the issue is likely to have effected a much larger number of people.
Finlay continued: “I suspect every single adoption agency in the country is involved, that’s 150,000 babies, it would be amazing if at least ten percent of them were not illegal.
“The bottom line is these people need their identity. They have a right to their background, who they are, where they came from. That trumps everything else.
“People have an absolute right to know.”
A detailed study of records from various adoption agencies in Ireland will now take place, in an attempt to identify where these illegal adoption practices took place.
Irish Minister for Justice Charlie Flanagan admits it is “highly likely” that other agencies were involved.
“I feel the likelihood is other agencies were involved in similar practices but I await the evidence before any conclusive comment can be made,” he said.
“But I would find extraordinary if only one agency was engaged in these practices.”
The 126 identified cases of incorrect adoption records all came from St Patrick’s Guild of Dublin.
It is expected that illegal adoptions were arranged throughout numerous other institutes during the same period.
Irish Taoiseach Leo Varadkar described the discovery as “another dark chapter in our history”.
He added that the currently known cases could be “the tip of the iceberg” and that the investigation into the hundreds of thousands of adoption records is a “potentially a mammoth task”.