Department of Justice secretary general Brian Purcell was accused of putting on a “farcical” performance and “talking down the clock” during an appearance today before the Oireachtas Justice Committee to discuss the Guerin Report.

Mr Purcell repeatedly refused to answer questions about the events leading to the retirement of former Garda commissioner Martin Callinan, including visiting Mr Callinan’s home the night before he announced he was stepping down.

He described the visit as “unusual” and said it had never happened before but said he was precluded from answering questions as a commission of inquiry into the matter was soon to begin under Mr Justice Nial Fennelly.

Mr Purcell said he was not “hiding behind anything ” and would answer any questions the committee had once the commission finished its work.

Committee chairman David Stanton (FG) said that, as the committee was not a court or a tribunal, it was within its remit to question him on that issue.

“The truth cannot change if it’s the truth,” Mr Stanton said.

Mr Purcell said he had “no wish to obstruct the committee” but found himself in a difficult situation.

Independent TD Finian McGrath said it was “unacceptable” that a senior public servant would behave as such, accusing Mr Purcell of “talking down the clock”. “You’re also costing the taxpayers of this country more money with this fudge and by hiding behind legislation,” he said.

Sinn Féin TD Pádraig MacLochlainn said the situation was “farcical ”.

Mr Purcell said giving evidence in public could “undermine or prejudice” the commission’s work and would be unfair on himself when it came to giving evidence. He denied speaking to the Minister for Justice, former minister Alan Shatter or officials from the Taoiseach’s department ahead of his appearance.

Asked by Senator Katherine Zappone (Ind) about the department’s response to allegations of Garda malpractice raised by whistleblower Sgt Maurice McCabe, which were the basis for the Guerin Report, Mr Purcell said the allegations had been investigated within the force and sent to the Garda Ombudsman Commission and the Director of Public Prosecutions, which did not seek to prosecute.

He said it had been the practice of the department and successive ministers to place considerable reliance on what they were told by the Garda commissioner.

Mr Purcell said the department had responded to correspondence received from Sgt McCabe in September 2012 with a series of letters seeking his permission to forward the dossiers to Garda commissioner, which he considered necessary as it appeared Sgt McCabe felt it inappropriate to have the Garda or GSOC investigate them. The impasses continued until December 2013, the committee heard.

He said some of the “relentless criticism” of staff in his department “is not well founded” but he recognised confidence in it had been damaged and must be restored.

Mr Purcell said he had “no hesitation” in apologising to those affected by shortcomings in the department, including to the whistleblowers themselves.

Asked by Ms Zappone if he regretted the fact the department did not undertake and investigation into Sgt McCabe’s claims, Mr Purcell replied that with “the benefit of hindsight...maybe we would have looked at it differently”.

He was satisfied the way the case was viewed “was reasonable in the circumstances” and given the “limitations” to the whistleblower structures in place at the time, which he said were “not fit for purpose”.

Asked about a transcript of a conversation between Sgt McCabe and former Garda confidential recipient Oliver Connolly, in which Mr Connolly is alleged to have told the garda to drop his complaints as the minister Alan Shatter would “go after him”, Mr Purcell said he thought there was “no way” Mr Shatter would say such a thing.

Asked about the refusal of Mr Shatter’s successor France Fitzgerald to express confidence in him on her appointment, Mr Purcell said he could “perfectly understand” a new minister not rushing to do so.

“It’s not a comfortable position for me to be in,” he said. “I can understand perfectly why the minister would take that approach.”