Former Fine Gael senator Mr Liam Cosgrave has accused lobbyist Mr Frank Dunlop of lying in his evidence to the Flood tribunal.
Mr Cosgrave argued today claims by Mr Dunlop that he took money to support rezoning motions for land in South Dublin while a county councillor were "inventions".
Mr Cosgrave specifically denied receiving £2,000 in 1992 from Mr Dunlop in return for supporting a motion to rezone 108 acres of land in Carrickmines.
The lands, which were on the western side of the Carrickmines Valley, had previously been deemed unsuitable for development in a report submitted by the Dublin County Manager. The report cited the lack of road access and the uneven terrain as likely to impede development.
Counsel for the tribunal, Mr John Gallagher SC, this morning accused Mr Cosgrave of "flying in the teeth" of stated county council policy in voting to have the lands rezoned.
"It was an irrational decision, was it not?" he asked. Mr Cosgrave replied: "I don't accept that".
Mr Gallagher said: "It was Mr Dunlop's evidence that he bought your vote for £2,000." Mr Cosgrave answered: "That's a lie".
Mr Gallagher then asked Mr Cosgrave why he thought Mr Dunlop would lie about giving him money.
"Maybe for tax reasons or he may have done a deal with the tribunal," Mr Cosgrave replied.
"But he was a close friend of yours," said Mr Gallagher.
"He never gave me money for a vote. He invented meetings and so called bribes. It never happened," said Mr Cosgrave.