The Sinn Féin leader has said information provided to the Dáil last week about the age of the teenager who received an inappropriate text from former Sinn Féin Senator Niall Ó Donnghaile was wrong.
Mary Lou McDonald said it was then her understanding that the young person was 17 years old at the time, based on information provided when they joined Ógra Sinn Féin.
The young person has since made it clear that they were 16 years of age, she said.
Ms Lou McDonald told the Dáil that she has written to the young person and their mother offering a full, unequivocal and sincere apology.
She said what happened was wrong and no young person should have experienced that.
She added that she was sorry for the hurt caused by her words in the statement she made when Mr Ó Donnghaile resigned last December.
“That was never my intention and I apologise to that person for issuing that statement,” she said.
Meanwhile, Sinn Féin’s deputy leader and Northern Ireland First Minister Michelle O’Neill has also corrected the record at Stormont regarding the age of the teenage boy.
In a statement in the Assembly chamber this morning, Ms O’Neill said she “fully accepted” the age and wanted to correct the information on the record.
She said it was her understanding that the young person was 17 based on the information he had provided in his application to join Sinn Féin.
“This information was wrong. Over the weekend the young person made it clear that he was in fact 16 at the time and I fully accept this,” she added.
“This morning I want to put on the record that he was in fact 16 years of age when these inappropriate texts were sent.”
The First Minister also repeated her apology to the teenager.
“What happened to this young person was wrong. Niall Ó Donnghaile’s behaviour was unacceptable and entirely inappropriate and no young person should have experienced that,” she said.
“As I said yesterday I am absolutely so sorry for the hurt caused by the statement issued following his resignation.”
Ms O’Neill had been facing calls to return to the Assembly after the DUP submitted an urgent question.
She has also been asked to return to a meeting of Stormont’s Executive Office Committee tomorrow for further questioning, but this has not yet been confirmed.
Ms O’Neill also told the Northern Ireland Assembly that a Sinn Féin member has resigned from the party after admitting involvement in damaging the portrait of a former DUP lord mayor at Belfast City Hall.
Ms O’Neill said: “Yesterday a Sinn Féin employee who worked in the Assembly made the party chief whip aware of their involvement in an incident regarding a portrait in Belfast City Hall.
“This took place on Saturday October 19. The employee was immediately suspended and we notified the PSNI.
“The employee has now resigned from their employment and their party membership.”
Additional reporting Vincent Kearney