The allegations specified corruption up to assistant commissioner level in the force, suggesting that two senior officers were involved in widespread planting of evidence on suspects.

The allegations were received by deputy Jim Higgins in April 2000 and he presented them to then justice minister John O'Donoghue.

The seriousness of the allegations finally led to the establishment of the tribunal.

Next month, a module relating to the allegations is to be heard by the tribunal. According to Higgins' statement, seen by the Sunday Tribune, he believed the source was PJ Togher, a retired garda and friend of the Raphoe publican, Frank McBrearty. In his statement to the tribunal, Higgins says he received a fax from McBrearty outlining the allegations.

"I asked Mr McBrearty who gave him the document and he indicated that it came from 'my friend'. Often in our previous conversations, Mr McBrearty had used the phrase 'my friend' when speaking of Mr PJ Togher. On this occasion I understood his use of the term 'my friend' to mean Mr Togher. Mr McBrearty stated to me that he had forwarded the document to me in confidence."

Higgins also states that he had met Togher previously, when the retired garda accompanied McBrearty to Leinster House to meet him. Higgins' statement is the first time that the author of the anonymous allegations has been identified.

The allegations began by saying, "Confidential information has come to hand from a serving detective inspector of An Garda Siochana concerning the Garda investigation in the Donegal division."

It went on to state that the now disgraced detective sergeant John White was being protected by investigating officer Kevin Carty and assistant commissioner Tony Hickey because both men had conspired with White in the planting of evidence in previous investigations in Dublin.

The allegations were found to be completely without foundation, but coming on foot of other allegations emanating from Donegal, it was decided that a tribunal would be required to investigate the whole question fully.

The allegations led to a challenge in the High Court and the Supreme Court after the tribunal ordered that Higgins and Labour TD Brendan Howlin hand over phone records to assist the tribunal in identifying the source.

Higgins dropped his challenge when McBrearty released him from confidentiality, but McBrearty didn't identify where he received the document and had claimed that the source was a member of the gardai. Howlin lost his challenge in the Supreme Court.

Judge Frederick Morris will begin hearings into the anonymous allegations module in January.