Former Fianna Fáil TD Mr Liam Lawlor has accused the leader of the Labour Party, Mr Pat Rabbitte, of making "outrageous, malicious" allegations against him.
In the Dáil this week, Mr Rabbitte pointed to Mr Lawlor as one of those who benefited to the tune of €13 million from the sale of lands needed to build the M50 motorway.
In a three-page statement last evening, Mr Lawlor said he had repeatedly denied owning or having a beneficial interest in the lands.
"The comments by Mr Rabbitte are outrageous, malicious and at total variance with the facts and were they stated outside the confines of the Dáil, they would be actionable," he said.
Mr Lawlor claimed that he has suffered from "hysterical, vindictive" media coverage.
Last night, a spokesman for Mr Rabbitte refused to respond. "We would not dignify anything Mr Lawlor would say with a comment."