Sinn Fein TD David Cullinane has rejected Drew Harris' comments that the Provisional Army Council oversees the political party and the IRA.
Speaking at a passing out ceremony, the Garda Commissioner said the force's assessment "does not differ" from the PSNI.
A PSNI-MI5 report from 2015 claimed both the IRA and Sinn Féin are overseen by a council with a political strategy.
The PSNI reiterated its view last year, while Sinn Féin has dismissed the assessment as 'nonsense'.
Drew Harris said he agrees with the PSNI view.
Deputy Cullinane told The Last Word there's no evidence of this, and rejected the comments.
"This is all coming on the back of an historic election where Sinn Féin won more votes than Fianna Fáil and Fine Gael, and we're seeing more of these attacks from both of those parties.
"Let me be clear: the IRA is gone, gone, gone, and will not be coming back.
"The war is well, well over and the vast majority of people on this island know that".
"The only people who influence Sinn Féin are the membership of Sinn Féin".
"Where is the evidence that there has been any activity by the IRA since 2005, when they made that historic statement.
"There has been absolutely none because it doesn't exist.
"It's members were stood down, it's structures were stood down - it exerts no influence whatsoever.
"It can't come back to make statements because it simply doesn't exist - so all of these calls on the airwaves to do things that it can't do are just ridiculous".
Main image: Garda Commissioner Drew Harris holds a press conference following a special meeting of the Police Authority at Dublin Castle | Image: Niall Carson/PA Archive/PA Images