Anonymous complaints must be treated with caution but can be starting points for inquiries by the Public Offices Commission, the Comptroller and Auditor General has told an Oireachtas Committee.
Mr John Purcell said there was a "difficulty" with anonymous letters, which tended to fall into three categories.
Some were "frivolous", some "vexatious", but there were others which were "well-backed, with documentation and so on", where there might be good reasons why the complainant could not give his or her name.
Addressing the Joint Committee on Finance and the Public Service, he said such a complaint should not form the basis for a formal investigation. "But any commission would be obliged to follow up on cases where there is serious back-up for an anonymous letter."
Mr Michael Finneran (FF) expressed concern that a well-timed "strike" against someone could decide an election, before the commission had a chance to prove an allegation wrong.
Mr Purcell said that initial inquiries were "very much within and confidential to the commission". However, he admitted there might be a problem "if a rival goes to the media and says: `I have reported so and so to the commission.' If you throw enough mud, some of it may stick. But you can't legislate for that".
The Ombudsman and chairman of the commission, Mr Kevin Murphy, told the committee there was a "significant gap" in the body's remit on political donations.
If a donation was "personal" - given by a family member or friend - and the recipient was satisfied it had no political significance, it did not have to be reported. Mr Murphy suggested that the remit might be broadened to include the reporting of personal donations.
The commission presented a report of its progress to date, which shows that two of the 30 candidates from the Dublin North and Limerick East by-elections last March have yet to submit election expenses statements, although the deadline was May 6th.
