The Fennelly Commission has concluded that the visit by former secretary general of the Department of Justice Brian Purcell to the home of former garda commissioner Martin Callinan was the immediate catalyst for Mr Callinan's retirement last year.
Mr Callinan told the commission the "direct cause of his decision to retire (on 25 March 2014) was the visit from Mr Purcell, and the message conveyed by the Taoiseach during that visit".
The then commissioner said he wished to retire in three months, the Taoiseach then considered the issue overnight and said the retirement would have to take place with "immediate effect", while maintaining it was Mr Callinan's decision.
The commission said "it must add" the decision to retire "cannot be seen in complete isolation from other contemporary events concerning An Garda Síochána and the Commissioner personally".
Taoiseach Enda Kenny said the charge made against him that he sacked Mr Callinan "doesn't stand up."
Speaking on RTÉ's Six One News, Mr Kenny said: "The report is clear and unambiguous in its findings that not only was there no dismissal or sacking of the garda commissioner, it was never even mentioned at the meeting."
The Fennelly Commission's report has concluded that the visit by the former secretary general to the home of Mr Callinan was the immediate catalyst for his retirement.
However, the report also stated Mr Callinan decided to retire and that he could have decided otherwise.
Mr Kenny said the commission found that he "had no intent to pressure the commissioner to retire, never mind be dismissed or sacked."
Mr Kenny said it was correct that he sent Brian Purcell to Mr Callinan's home to make it clear the grave concerns that the Taoiseach had.
But he added: "The commission points out that the commissioner did have other options, and that he decided not to take up any of those."
Mr Kenny said there is a process to sack a garda commissioner but the commission's report is clear that such a move was never discussed at the meeting on 24 March 2014.
The commission further concluded it was an "error of judgement" for the then garda commissioner to postpone making a written report in relation to phone recordings in garda stations, saying he was aware of the issue from October 2013.
It says he could have made a partial or "general" report pending the gathering of facts.
It says he was under an obligation from mid-November pursuant to the Garda Síochána Act to ensure the Secretary General and the Minister for Justice were kept fully informed.
It says in sending a letter in March 2014 he was "unquestionably" complying with obligations - "though he was in delay".
The commission concluded that the then garda commissioner was "not adequately" informed by his management about the recording issue.
Both the Taoiseach and the Attorney General, the report says, were of the opinion it would be "inappropriate" for them to contact the commissioner directly in relation to these issues.
Taoiseach Enda Kenny says he was the strongest defender of the former garda commissioner in public and in private https://t.co/HL2IKG8BOY— RTÉ News (@rtenews) September 1, 2015
In its conclusions the commission said it accepted the Taoiseach "did not intend to put pressure on the garda commissioner to retire."
It details the background to his retirement in relation to a number of matters.
It said the then garda commissioner "interpreted" the message delivered to him "with all its intendant circumstance" as an "indication" he should consider his position.
The report said this was a "reasonable" conclusion for the garda commissioner to reach.
However, it added that while the commissioner decided to retire "he could have decided otherwise". But he did not want to become embroiled to legal "or other conflict" with Government.
The interim report continues saying while Mr Callinan was "conscious of other recent events which had resulted in controversy for himself and for An Garda Síochána, the immediate catalyst" for his decision to retire was the visit of the Secretary General of the Department of Justice to his home.
The report says the events leading up to the retirement of Mr Callinan was "beset by serious information deficits and multiple failures of communication".
It says it would "undoubtedly have made a significant difference to events as they unfolded" if the commissioner had been able to report he had formally informed the Department of Justice about issues in relation to the recordings at garda stations two weeks before Mr Purcell's visit to his home.
The report finds that "although the the Attorney General considered that she had discovered a matter of the gravest possible public concern regarding An Garda Síochána, and, as we shall see, she believed it warranted being raised with the Taoiseach, no contact was made with nor inquiry made of either of the two people most obviously concerned and responsible".
Earlier, in a statement, Mr Kenny said it was "deeply regrettable" and "very significant" that he or other senior officials were not told about a letter from the commissioner on the issue of gardaí taping phone conversations at a number of garda stations.
The report criticised the delay in submitting this letter from the Department of Justice as they had received the letter two weeks earlier.
Mr Kenny said: "Had this letter been brought to my attention, a meeting between Mr Purcell and the then commissioner would not have been necessary and this letter could have been presented to the Cabinet the following day."
The report investigated the sequence of events that led up to the retirement of Mr Callinan on 25 March 2014.
It also examined the events surrounding the letter the former commissioner sent to the Department of Justice two weeks earlier (10 March 2014) informing the minister that phone calls to garda stations had been recorded.
The commission interviewed politicians and officials, former and current, at the highest levels in the Government, the Department of Justice and An Garda Síochána, including the Taoiseach, the Attorney General, the Secretary to the Government, and former Minister for Justice Alan Shatter, former commissioner and Mr Purcell.
Mr Purcell visited Mr Callinan at his home the night before he retired.
The Taoiseach said he sent Mr Purcell there to convey to the former commissioner his concerns over the recording of phone calls in garda stations.
Mr Kenny was the only person to receive a copy of the final interim report earlier this week.
Shatter welcomes report's findings
In a statement, former Mr Shatter said he welcomed the commission's finding that prior to the retirement of Mr Callinan he did not receive or had no knowledge of the letter on the "garda taping issue".
Mr Shatter said lessons needed to be learned from the Fennelly Report.