Former minister for justice Alan Shatter has said the Fennelly Commission rejected evidence given by Taoiseach and Attorney General and that in any other parliamentary democracy such an outcome would be "a resigning matter".

Mr Shatter said the report discloses more a "cock-up than conspiracy" in An Garda Síochána but said both Taoiseach Enda Kenny and Attorney General Máire Whelan have questions to answer.

Mr Shatter said the report makes it absolutely clear that Ms Whelan's warning of the gravity of the situation at the time has been proved to be a "gross and serious misjudgment".

Speaking on RTÉ's Morning Ireland, he asked if she will take responsibility for the alarmist advice she gave.

"Most seriously of all why did each of them give evidence to the Fennelly Commission of Investigation which Judge Fennelly rejected - and I think that's a very serious issue.

"In any other parliamentary democracy when the Attorney General of the day or the Taoisech of the day would give sworn evidence at a Commission of Investigation or a tribunal that was rejected by the person appointed to draw conclusions, that would be a resigning matter."

The commission was established in March 2014 to examine the circumstances surrounding the retirement of then garda commissioner Martin Callinan, and the taping of phone calls at garda stations.

Mr Shatter said Mr Kenny and Ms Whelan now have questions to answer about why neither of them contacted him as minister for justice when they first became aware of the matter.

Mr Shatter said we now know Ms Whelan had first learned about the recordings in November 2013 and failed to inform the Taoiseach or the minister of justice.

Labour leader Brendan Howlin has said the report raises very profound issues and lays out how dysfunctional management in the organisation has been.

Mr Howlin, who was a Cabinet minister when the commission was established, defended the response of Mr Kenny and Ms Whelan saying the unknown extent of the impact of the recordings at the time would have been very concerning.

Also speaking on Morning Ireland, he said that the absence of oversight in An Garda Síochána is clearly shown by the report and suggested "we are numbed or desensitised to some of these issues".

He said it was just fortunate the "wholesale, illegal, unauthorised recordings" in garda stations did not impact on criminal cases.

Mr Howlin said very clear management of these issues is now needed, something he said "we clearly don't have".

He said Ms Whelan had at the time acted cautiously.