The former Progressive Democrats leader, Mr Des O'Malley, tonight denied any role in editing of a statement to the 1970 Arms Trial.
Documentation produced by RTÉ's Prime Timeprogramme last night showed the statement by a former head of military intelligence, Col Michael Hefferon, was heavily edited before the trial.
In a statement Mr O'Malley said: "I want to make it clear that I did not engage, as was implied last night, in altering anyone's evidence nor did I approve or condone of anyone else doing so."
The edited changes were intended to minimise the involvement and knowledge of the then minister for defence, Mr Jim Gibbons, in relation to arms importation attempts.
Mr O'Malley said he particularly took issue with the assertion that if state counsel knew the full extent of Colonel Hefferon's proposed evidence they might have taken a different view about the prosecution and not gone against some defendants.
He also said Col Hefferon's statements and allegations about Mr Gibbons did not appear to be new: "[They] were first voiced in full in public at the first trial in Septmber 1970 and were repeated at the second trial in October 1970."