Fianna Fáil TD Eamon O Cuiv says former Taoiseach John Bruton is guilty of "revisionism" by claiming there was no mandate for the 1916 Rising.
The former Fianna Fáil deputy leader and grandson of Éamon de Valera also said Mr Bruton was on a "crusade" and that his views relate more to developing a "United States of Europe super-power" than the 1916 Rising.
Mr O Cuiv was speaking at the launch of a new book on the life of Jeremiah O'Donovan Rossa, the Fenian leader and member of the Irish Republican Brotherhood whose funeral was made infamous by the graveside oration by Patrick Pearse.
The funeral, which will be re-enacted today, is considered a turning point in the course of Irish history and was a major contributing factor leading to the Easter Rising and War of Independence.
Mr O Cuiv and Mr Bruton have frequently clashed on the issue of the 1916 Rising, with the former Taoiseach insisting there was no mandate for the violent rebellion.
He has also said that a free and independent Ireland could have been achieved without such loss of life and that Britain had agreed to Home Rule, as campaigned for by the Irish Parliamentary Party leader John Redmond.
Mr O Cuiv said Mr Bruton had benefited while in office from the sacrifice of those who gave their lives for Irish freedom.
"There has been a lot of revisionism in recent years, particularly about the demo- cratic mandate for 1916 led by ex - Taoiseach John Bruton, who enjoyed in office the fruits of the struggle for Irish independence," Mr O Cuiv said at the launch of Shane Kenna's book, 'Jeremiah O'Donovan Rossa: Unrepentant Fenian', in Glasnevin Cemetery this week.
"He (Bruton) said there was not a democratic mandate for the Rising," Mr O Cuiv said, before outlining five points he felt showed there was a demand for such an action among Irish people.
He said O'Donovan Rossa's election to parliament, and the fact 200,000 people attended his funeral in 1915 indicated popular support for his cause.
"Of course, just as Rossa's funeral was used to promote the then current aims of the Irish Citizen Army and the Volunteers, I believe that John Bruton's crusade has more to do with his wish for a United States of Europe super-power, complete with a super-power army and army industry, than it has to any real belief he claims to have that John Redmond was a pacifist."
Mr O Cuiv said he doesn't believe Mr Bruton's stance on the uprising has "anything to do with 1916". He said by promoting that Ireland should have accepted Home Rule back then, in today's context, he was calling for the development of Europe as a super-power.
One of the conditions of Ireland accepting Home Rule was that it would retain military ties to Britain, which may thave resulted in Irish involvement in World War Two.
"I think it has more to do with John Bruton's view of a United Europe and an army and the whole lot," he said.
In response, Mr Bruton said there "was no need for anyone to be killed to attain Irish independence" and that the Irish Parliamentary Party was "unjustly denigrated" by Pearse's oration.
"The O'Donovan Rossa funeral was used by the IRB to glorify violent methods. That was wrong," he said.
"We can commemorate whatever we wish, but moral principles do not change, just because 100 years have passed."