Former chairperson of the Public Accounts Committee John McGuinness has called on former garda commissioner Martin Callinan to clarify his intentions during a secret meeting between them two years ago.

In the Dáil last week, Mr McGuinness said he met the then-garda commissioner at a car park in January 2014 after Mr Callinan contacted him directly.

Speaking on RTÉ's This Week, Mr McGuiness alleged that Mr Callinan attempted to undermine the credibility of garda whistleblower Sgt Maurice McCabe during the meeting.

The Fianna Fáil TD said he had heard these claims before and he had put them to Sgt McCabe and he was satisfied Sgt McCabe was trustworthy.

No documents were produced during the meeting to support the claims, according to Mr McGuiness.

He said he is raising this meeting now because the finger is being pointed at Sgt McCabe and questions are being asked about his credibility.

He also said current Garda Commissioner Nóirín O'Sullivan needs to make a statement in relation to what was known and who was involved in, what he says, were efforts to undermine Sgt McCabe.

Mr McGuinness said questions need to be answered following the O'Higgins Report and until then, he cannot express confidence in Commissioner O'Sullivan.

Sinn Féin's Pearse Doherty has said it was "baffling" that the former garda commissioner would request a meeting with the head of the Public Accounts Committee at a secret location. 

Also speaking on RTÉ's This Week Mr Doherty said he was surprised Mr McGuinness did not reveal his meeting with Mr Callinan sooner. 

Mr Doherty said this was an error of judgement on Mr McGuinness's part, considering the seriousness of the matter.

Meanwhile, Government Chief Whip Regina Doherty has said she expects more issues around allegations of garda malpractice to emerge after an audit of the culture of the police force is carried out.

The audit has been demanded by the Policing Authority and Ms Doherty said she believes the Authority could have a role in handling complaints from gardaí.

Speaking on RTÉ's The Week in Politics she said there has to be somewhere other than within the force for gardaí to bring their concerns.

Sinn Féin TD Martin Kenny has repeated his call that the allegations of garda malpractice in Leitrim, which he outlined in the Dáil on Thursday, should be investigated by an independent commission.

Mr Kenny said these allegations may have been examined in the past but they have never been investigated. 

Meanwhile, Independent TD Maureen O'Sullivan has said an international effort is required to go after the money of criminal gangs.

The TD, who represents the north inner city in the Dublin Central constituency, said the ministers for finance and justice must engage with their EU colleagues to root out havens for criminals' money across Europe.

Elsewhere, lawyers for a young garda whistleblower have questioned whether alleged death threats against him were "legitimate" or whether they were being used to justify ongoing surveillance against him, according to a letter sent to Commissioner Nóirín O'Sullivan.

RTÉ's This Week has learned that solicitors Kilfeather and Company, acting for Garda Keith Harrison, wrote to Commissioner O'Sullivan earlier this month raising serious questions over the issues relating to the alleged threats to his life.

It is understood that the letter outlines that while gardaí told Garda Harrison that the suspect was overseas, he did an online search and found that the suspect had attended a court hearing at a district court in Ireland, also attended by numerous gardaí, and at which he was granted bail.

The letter said that Garda Harrison had been given no explanation as to why the suspect was allowed to walk out freely from the court and was not arrested for questioning at that time in relation to the alleged threat to kill a garda, if the death threat was indeed genuine.

However, at the same time it says gardaí informed Garda Harrison that, because of the perceived risk, they would be increasing regular surveillance of his own home and movements.

In a previous complaint to the Garda Síochána Ombudsman Commission, Garda Harrison said the constant surveillance and monitoring by gardaí of his family home amounted to harassment.

The letter does not make any accusation of wrongdoing against any specific member of the force but raises questions over how serious the alleged threats were if the suspect was not apprehended at that time.

The solicitors described the development as "disturbing" and it is understood that they informed the garda commissioner that it was their intention to refer the matter to the attention of GSOC.

The letter said this latest threat is one of several which he has been informed of - some of which were made anonymously on internet sites - and all of which were used as a justification for regular and visible patrolling of his house by gardaí.

Asked to comment on the issues raised in the letter from the garda's solicitor, a spokesperson for the garda commissioner said that it would be "inappropriate to comment on an ongoing and active investigation".

Garda Harrison has complained to GSOC that he was subject to mistreatment within the force after he arrested another garda for suspected drink driving when he was based in the midlands.

Independent TD Clare Daly, who is familiar with the case, said the latest development raises questions over whether the death threats were "just a ruse, a story, to facilitate garda authorities monitoring his behaviour, which he as a whistleblower found incredibly traumatic and intrusive?"