Former Fianna Fáil TD Mr Liam Lawlor has been accused of lying to the Mahon tribunal about his involvement in a land deal in Lucan.
Judge Alan Mahon said Mr Lawlor's previous evidence that he had no connection to a deal involving the Coolamber lands opposite his home in Somerton was "a lie and nothing short of false".
In his previous evidence to the tribunal, Mr Lawlor claimed that he had no legal or beneficial interest in the companies involved in the purchase of the 55 acres.
At the time Mr Lawlor said his only involvement was as "an adjoining landowner" who saw an "exceptional development opportunity".
He said he advised beef tycoon Mr Larry Goodman - with whom he had a close working relationship - to purchase the lands.
However the tribunal has learned that Mr Lawlor received £350,000 for his part in the deal.
The money was dressed up as a loan to Mr Lawlor from a company with an address in the British Virgin Islands
It has now emerged that Mr Lawlor was a shareholder in the company used to purchase the land along with developer Mr Jim Kennedy and solicitor Mr John Caldwell with the finance coming from Mr Goodman.
In his previous evidence to the tribunal, Mr Lawlor repeatedly denied any involvement in the deal.
Judge Mahon said Mr Lawlor's assertion that he had forgotten about his involvement "defies belief".
Earlier it emerged Mr Lawlor failed to declare interests in five property companies involved in land transactions in Dublin in his previous evidence to the tribunal.
In his testimony to the tribunal in December 2000, Mr Lawlor was repeatedly asked to state his interests in lands or companies connected with land deals in Dublin.
At the time Mr Lawlor told the tribunal that he owned land in Lucan and had an interest in one property company.
However the tribunal has obtained a 1995 letter from a solicitor acting on Mr Lawlor's behalf in which Mr Lawlor claims an interest in five other property companies.
The solicitor, Mr Noel Smyth, was writing to another solicitor Mr Caldwell whom Mr Lawlor was in dispute with at the time.
Mr Lawlor claimed Mr Smyth was not acting on his instructions and that he had not been shown the letter.
