The developer Tom Gilmartin has identified Councillor Christy Burke as the Sinn Féin representative who he says warned him to stay out of Clondalkin.
Mr Gilmartin told the Mahon Tribunal that the threat was made by Mr Burke, who was accompanied by two men in dark clothing and sunglasses.
Councillor Burke denies the allegation.
Earlier, Mr Gilmartin alleged that an anonymous bank official told him that Bertie Ahern had £15m in an offshore account.
Mr Gilmartin told the tribunal that he was suspicious about the calls and felt it may be a set up.
He said he received the two anonymous calls in 1998 but did not inform the tribunal until four years later.
The caller told him that developer Owen O'Callaghan paid money into offshore accounts belonging to Mr Ahern and Albert Reynolds.
Mr Gilmartin added that the caller alleged the two men had accounts in Jersey, Liechtenstein and the Dutch Antilles.
Mr Gilmartin said he was suspicious because he was previously warned by another anonymous source to steer clear of the allegations by Denis O'Brien.
Mr Gilmartin said he was told the allegation by Mr O'Brien that he had paid £50,000 to Mr Ahern was a set up to exonerate Mr Ahern.
And that after this allegation was proven false Mr O'Callaghan paid off Mr O'Brien's debts.
Meanwhile, the tribunal will be delayed further after it was announced today that former lobbyist Frank Dunlop will not be able to appear next week due to medical reasons.
Judge Alan Mahon said that Mr Dunlop is not expected to be able to give evidence until early July.
Mr Gilmartin is also unavailable next week, so as a result there will be no public sittings.
