Fianna Fail leader Micheal Martin has launched a scathing attack on the main governing parties in Northern Ireland while accusing the Irish Government of ignoring serious problems north of the border.
In an address at the annual Wolfe Tone commemoration at Bodenstown, Co Kildare, Mr Martin claimed the Democratic Unionists and Sinn Fein constantly put party interest ahead of the common good at Stormont.
Stressing that much work still had to be done to end division and sectarianism in Northern Ireland, he characterised Taoiseach Enda Kenny's attitude to cross-border matters as one of disengagement and complacency.
"Unfortunately too many people today think that the work is over - that we can take for granted what has been achieved," he said.
"This could be a mistake of historic proportions.
"The Irish Government has dramatically reduced its level of engagement with northern affairs. Given the effort that went into this process over a very long time by very many people, this sort of disengagement and complacency by our own Government is unacceptable.
"I know that these are hard words, but they are fully borne out by the reality. The Taoiseach has had the bare minimum of meetings concerning the north and has outlined not a single new item for his agenda. There has been no attempt to move the process to the next stage. There has been no push for initiatives to undertake vital anti-sectarian work. There has been no discussion of how the long-term roots of division and underdevelopment are to be tackled."
Mr Martin then turned his critical focus to the main parties in Northern Ireland, claiming the popular legitimacy of the power sharing institutions were in danger of being undermined.
"The Peace Process was always intended to be about more than an absence of violence," he said.
"The people of the north deserve a political system that delivers progress that demonstrates that politics works and which is about making their lives better."