Garda whistleblower Sergeant Maurice McCabe has given evidence to the Public Accounts Committee over claims of corruption in the penalty points system.

The committee heard around three hours of evidence from Sergeant McCabe.

It is understood he told them it was his first official interview in 18 months.

Several members have described his evidence as very clear, and very comprehensive.

It is believed he backed up concerns in the Comptroller and Auditor General's report regarding the flaws in the penalty points system.

Sergeant McCabe spoke in generalities and referred to clusters in certain areas.

He also said systems are more transparent since the C&AG’s report. He said he had pride in his uniform.

He welcomed the Garda Ombudsman Commission's investigation and said he will fully co-operate with it.

A transcript of his evidence will not be made available to protect everyone involved.

PAC Chairman John McGuinness has said that if Sergeant McCabe applies for a transcript of today's proceedings, the committee will consider it.

However, he said he had no doubt that the transcript would be made available to him and his legal team.

Mr McGuinness also said that the committee will decide if the transcript should be given to its members.

He added that the matter had to be cleared by Sergeant McCabe's legal team.

He said he has to be satisfied in the first instance as there may be issues that could affect him.

Mr McGuinness earlier said the committee "got a unique insight into the way the fixed charge system worked at an operational level".

He added: "No garda officer was named, third parties who had tickets cancelled were not named, no instance was cited where a member of the force, a member of the public, or any outside body was accused of acting wrongly.

"The evidence of Sergeant McCabe focused on his experience as a member of the Garda Siochána and the concerns he had around the penalty point system, which led him to give evidence."

This afternoon's hearing went ahead despite calls from Garda Commissioner Martin Callinan and Minister for Justice Alan Shatter for it not to proceed.

On Monday, Mr Shatter referred the allegations to the Garda Síochána Ombudsman Commission.

The PAC decided to proceed with its inquiry on Tuesday, but agreed to impose restrictions on what evidence Sergeant McCabe could give.

Independent TD Shane Ross said earlier that it was still important that the PAC heard from Sergeant McCabe, despite the restrictions.

Mr Ross said he personally had misgivings about the session being held in private, but that it was a matter that was in the public arena and of huge public interest.

He said it was imperative that the PAC showed its independence as an executive.