Former developer Tom Gilmartin has denied at the Mahon Tribunal that he forged his diary to back up his claim of a meeting with ministers at Dáil Éireann.
Lawyers for Taoiseach Bertie Ahern said the allegation of a demand for £5m was an example of Mr Gilmartin spicing up his allegations.
Mr Gilmartin claimed that the £5m demand was made to him by an unidentified man after after he left a meeting with ministers in February 1989.
But lawyers for Mr Ahern said this allegation is first recorded by tribunal lawyers in January 1999.
Colm Ó hOisín SC said Mr Gilmartin had not mentioned this allegation previously in statements to a Garda superintendent, with a Dublin Corporation official or in original tribunal interviews.
He said Mr Gilmartin was recorded in all three interviews as saying it was the late Liam Lawlor who demanded £5m.
Mr Ó hOisín put it to Mr Gilmartin that he decided to spice up his allegations after the relevation in September 1998 of the £50,000 payment to Padraig Flynn made him realise the publicity he would get.
He said Mr Gilmartin had changed his evidence on the date that he alleged the meeting with ministers took place after Mr Ahern was able to prove he was not there.
But Mr Gilmartin denied forging an entry in his diary.
