Former undeclared payments made to him by RTÉ between 2017 and 2022.
host Ryan Tubridy says he "should have asked questions" about theIt was announced on Thursday that RTÉ admitted paying Mr Tubridy €345,000 more than what it stated publicly it was paying him.
The broadcaster said the money was paid between 2017 and 2022, and was above his annual published salary.
The payments were uncovered after a “transparency” issue about payments made to Mr Tubridy was identified during a routine audit of RTÉ’s 2022 accounts in March.
In an updated statement issued on Friday through NK Management, Mr Tubridy said RTÉ’s "accounting treatment and publication of payments made to me between 2017 and 2022 contained serious errors".
"While I have no responsibility for the corporate governance in RTÉ or how or what they publish in their accounts, when my earnings were published I should have asked questions at the time and sought answers as to the circumstances which resulted in incorrect figures being published."
He said he apologises "unreservedly" for failure to do so.
"For the avoidance of doubt, all my earnings from RTÉ have at all times been included in my company’s accounts that were prepared by my accountant and filed with the Companies Registration Office and all my taxes are up to date," he said.
He said that his filed accounts with details of his earnings "have previously been reported on in the media".
"At the centre of all of this is trust. The trust of colleagues in RTÉ and the trust of a great many people who listen to my show," he said.
Mr Tubridy added that it is "simply not true" that he did not take a pay cut over the last number of years.
"Over the period of my contract with RTÉ, I have been asked to take several reductions in salary and I did. Indeed, between 2012 and today, my pay from RTÉ was cut by approximately 40%."
The presenter also said that the controversy around the payments had no bearing on his decision to step down from
.Ending his statement, Mr Tubridy said he was "disappointed" that RTÉ decided he should not broadcast his radio show next week.
"I look forward to returning to the radio show, a job I love, as soon as possible and I hope my listeners and my colleagues appreciate my sincerity on this."
Earlier, RTÉ confirmed that Director General Dee Forbes was suspended from her employment on Wednesday.
The broadcaster said that investigative processes are ongoing.
The chair of the Public Accounts Committee has called for Ms Forbes to appear before it and give "an immediate and full examination of the hidden and undisclosed payments" Ryan Tubridy.
Sinn Féin TD Brian Stanley says what has happened under the watch of RTÉ's executive board is "utterly unacceptable and yet another serious breach of trust between our national broadcaster and the public."