“It was made by an individual,” said Mr Morrissey, who was nominated by Taoiseach Bertie Ahern as a PD senator in 2002.
He handed in a written note on being requested to name the individual, the project involved and the approximate time the inducement was offered.
His disclosure came at the end of questioning about his voting patterns impacting a leading development company when a Fine Gael member of Dublin County Council in the early 1990s.
The tribunal is investigating payments by Monarch Properties totalling more than £500,000 in the 1990s.
Tribunal lawyer Patricia Dillon SC said it was not suggested the payments, described by Monarch as political, were corrupt.
Almost half the amount went to 69 different politicians in connection with Monarch’s attempts to rezone its land at Cherrywood in south Dublin.
Questioned by Judge Mary Faherty, Mr Morrissey said he did not feel donations he received had influenced his voting.
The tribunal heard he supported a motion that allowed four houses per acre on land owned by Monarch but restricted other landowners in the area to one house per acre.
Mr Morrissey agreed it did appear arbitrary and that he had previously opposed higher density housing in the area. However, he said he was allowed to change his mind after listening to arguments from officials and councillors although he could not say at this remove what the arguments were.
Earlier, he denied there was any link between donations he got from Monarch and how he voted on projects sponsored by that company as a county councillor.
Records show he received £500 from Monarch in January 1994 and £750 in March 1996. Documents show Monarch executive Richard Lynn put in expenses in 1993, listing meetings with Mr Morrissey, but Mr Morrissey said he could not remember these.
Tribunal chairman Judge Alan Mahon asked Mr Morrissey why he had so many meetings with Mr Lynn, given that Cherrywood was outside his electoral area.
Illustrating his impartiality, Mr Morrissey cited an instance where he proposed a motion in favour of lands at Sommerton, owned by Monarch founder Phil Monahan — and then voted against it. The motion was lost by a vote, he said.