At the Flood Tribunal, Frank Dunlop has denied that his diary entries of meetings with county councillors in 1992 were forged.
He was responding to questions from lawyers for Fine Gael Councillor, Liam Cosgrave, who denies taking bribes from the former lobbyist.
Michael O'Higgins, SC, said another entry relating to Senator Don Lydon appeared to be wrong and asked if it was a forgery.
Mr Dunlop said one entry could have been wrong, but he denied any forgery.
He is being questioned about his note of a meeting with Liam Cosgrave in 1992 during which he claims to have given the Councillor £5,000 in cash to support a development.
