The Tánaiste and Minister for Justice has said the scale of the latest garda scandal, which caused almost 15,000 wrongful road traffic convictions, is "appalling and staggering".

It was disclosed yesterday that about 14,700 people convicted in the courts were prosecuted without a fixed-charge notice first being issued.

Gardaí now have to appeal all those convictions, have those court-imposed penalties removed and the State has to cover all costs, estimated to run into millions of euro.

Frances Fitzgerald said the discrepancy means "effectively it was across the whole system".

In a statement released this afternoon, Ms Fitzgerald said: “I have raised these issues with the Garda Commissioner and the Chairperson of the Policing Authority and have outlined my very serious concerns.

"The Chairperson of the Policing Authority, Josephine Feehily, has confirmed that the Authority will continue to examine these matters.

"In relation to the mandatory alcohol testing, solutions have been put in place and the Commissioner has advised me that she will take all steps necessary to ensure that this cannot reoccur.

"I have made it clear to the Commissioner that the practices that allowed this misreporting to happen within An Garda Síochána over many years need to be fully addressed and the new systems that she has put in place will need to be robust, tested and verified in the time ahead," added Ms Fitzgerald.

Earlier, Fianna Fáil's justice spokesperson said his confidence in Garda Commissioner Nóirín O'Sullivan will not be assured unless an adequate explanation is given for how the garda error occurred.

Speaking on RTÉ's Morning Ireland, Fianna Fáil TD for Dublin Bay South Jim O'Callaghan said that Commissioner O'Sullivan should take the lead in how this matter is being explained.

He said it is unacceptable that people were convicted in the courts for road traffic offences due to "a garda error" and that people need to know how this happened and who is responsible.

It also emerged that gardaí recorded 937,000 more roadside alcohol tests than had actually been carried out in a five-year period to 2016 - almost twice the real figure.

Mr O'Callaghan said this is "damaging the credibility of An Garda Síochána", adding that "they must come out with serious explanations about how these serious errors occurred".

He said gardaí have known about this issue for at least eight months and there is a need to know if the Government was made aware.

"Tánaiste and Minister for Justice Frances Fitzgerald needs to spell out exactly when she was informed about the litany of errors announced by An Garda Siochána yesterday," he said.

"She needs to explain what discussions she has had with the Garda Commissioner on these matters, and she needs to spell out to the Irish people what exactly is her understanding of how these errors occurred and who is responsible.

"My party and I are concerned that the manner of yesterday's announcement, and the lack of a coherent explanation from any quarter points to a lack of understanding of how serious this situation now is."

A spokesperson for the Department of Justice later said: "Obviously the issues which have arisen are matters of concern.

"While the Tánaiste welcomes the measures being taken to address these issues, she has asked to be kept informed of progress in this regard and in relation to ensuring issues of this kind do not arise again.

"The Policing Authority will have a significant oversight role in this regard."

Controversy is 'eroding public confidence' in gardaí - Howlin

Labour Party leader Brendan Howlin has said the controversy is eroding public confidence in An Garda Síochána, and called for Ms O'Sullivan to be replaced.

Speaking on RTÉ's Today with Sean O'Rourke, he said fundamental trust is really important and that has been seriously undermined by the latest series of events. 

He said there are two separate issues of concern: "One, that almost one million breath tests were taken and logged but never happened; and secondly, 15,000 convictions, people prosecuted in court, that should not have happened.

"For every actual breath test that took place, a second in statistical terms was actually recorded as having taken place and that didn't happen at all. Now that is beyond belief, it beggars belief that could happen and there is no answer to it."

He believes Ms O'Sullivan should be responding to the controversy and explaining what happened. 

"The buck stops with the person in charge. The commissioner has to explain in very real terms what happened here."

Sinn Féin leader Gerry Adams said public confidence in the management of An Garda Síochána will be further eroded by the revelations.

"All of these issues go to the very heart of public expectation and confidence in the integrity of our policing and justice systems. That necessary confidence in garda management does not exist at this time."

Independent TD Clare Daly said that the latest example of what she termed "garda indiscipline and mismanagement" is one scandal too far and someone needs to be held to account for it.

Speaking on the RTÉ News at One, Ms Daly said it is "really keystone cops stuff" and the Garda Commissioner has lost the authority of the force and the public.

She said the existing hierarchy in the force came from the same culture and ethos that has been found to be deficient and "it needs shaking up" and replacing.

She also said the Policing Authority does not have enough teeth, and questioned how long the Tánaiste knew about the matter and accused her of repeating a "mantra" in response to it.

Social Democrats TD Roísín Shortall has said the scale of the garda errors are huge and the falsifying of figures raises issues in relation to garda competence and integrity.

Speaking on RTÉ’S Six One, Ms Shortall said there has been no clear explanation as to why it happened, saying gardaí were "cooking the books".

She said it is yet another scandal in a long list of scandals and authorities have failed to deal with the problems over the years.

Ms Shortall said it is not enough to apologise and there have to be consequences.

She said the Tánaiste needs to ask that Garda Commissioner O'Sullivan to make a statement in the next week in relation to how the scandals have arisen and who is going to be held accountable.