McBrearty's call comes after Friday's release of sections of the latest three reports of the Morris tribunal, in which Justice Frederick Morris made several recommendations to the government about disciplinary problems in the gardai.

However, McBrearty has been critical of the Morris tribunal to date and believes the "full truth" about the Donegal scandal can be exposed only by a new public inquiry.

"I am calling on the government to establish a new public inquiry with an independent international judge or a current sitting high court judge, " he said. "That judge has to be given the power to appoint a team of international investigators to come in and be given powers to investigate the attorney general's office, the DPP and senior members of the Garda Siochana.

"The new inquiry should to ask why the Morris tribunal did not call vital witnesses in the last module. These witnesses could have exposed the whole truth about the night Richie Barron was killed, " McBrearty said.

The McBrearty family has persistently vented its anger at the Morris tribunal, arguing that the terms of reference of the tribunal were drawn up "to protect certain people from scrutiny".

McBrearty concluded: "The Irish state never got to the full truth of Kerry babies scandal, the Stardust fire and many of the abuse scandals. We will not let them get away without getting to the full truth of the Donegal garda scandal."