The SDLP has demanded that the Taoiseach, Mr Ahern, call a meeting of the Forum for Peace and Reconciliation to investigate the Government's proposed citizenship referendum.
In a strongly-worded private letter to Mr Ahern, seen by The Irish Times, the SDLP leader, Mr Mark Durkan, expressed "profound concern" about the proposed poll, due to take place on June 11th.
"I urge you to convene the forum not only to allow parties air and share their views, but to commission evidence and advice on key issues of concern," he wrote.
The SDLP's intervention has been matched by a decision of Fine Gael, Labour and the Greens to seek to have the referendum legislation referred to the Oireachtas Committee on the Constitution.
Sharply critical of the Government's action, the SDLP leader said it was clear that the constitutional amendments proposed would have implications for the Good Friday agreement.
"What those implications are is not fully clear. This not only makes the amendment's content questionable but renders unreasonable the hasty referendum date proposed to coincide with the European election," he said.
Following previous referendums, the Government had attempted to improve the level of public debates about issues such as the Nice Treaty to "counter the damaging effects of fear and confusion".
Given the implications for the agreement, "more collective consideration and respectful consultation" was warranted, Mr Durkan told Mr Ahern, in the letter sent last Monday. He particularly criticised the Government and the Minister for Justice, Equality and Law Reform, Mr McDowell, for failing to consult Northern parties before deciding to go ahead.
The legislation clearing the way for the referendum to be held alongside the local and European Parliament elections will be debated by the Dáil next week. The matter will be voted on the following week.
"It is perturbing that the Irish Government did not choose to raise its plans with Northern parties, not even in the context of the Review of the agreement's workings," Mr Durkan wrote.
"Even in the absence of a coherent working review structure, the Government has had the opportunity of the scheduled Tuesdays to brief and sound parties on a bilateral basis. "It seems that the choice was made not to engage the Northern parties on this matter but to instead dispose of our interests by way of a joint declaration with the British government.
"Such an approach raises serious concerns and damages confidence on a number of levels - and not just for people and parties in the North," Mr Durkan told the Taoiseach. The Good Friday agreement had offered "clear promises" about citizenship. "Therefore it should not be treated as the property of the two governments to arbitrarily reinterpret or adjust," Mr Durkan went on.
"Legitimate concerns about the effects of the proposed amendment will not be credibly assuaged by a dubious 'warranty' in the form of a joint declaration of unclear standing."
Given that the Democratic Unionist Party has been told that the agreement's "fundamentals" could not be renegotiated, Mr Durkan said, there was a "worrying irony" about the Government's intentions.
"It has not been lost on us that, while the DUP is properly told that the constitutional fundamentals of the agreement cannot be renegotiated, the Irish Government moves to revisit a key facet of its balanced constitutional essence. The precedent this would establish will hardly be lost on others.
"Nor will it be lost on people in the North that one effect of the proposed amendment would be to allow citizenship to be redefined and qualified by statute in future.
"The perceived lack of regard for the rights and insights of Irish citizens in the North, in the context of the proposed referendum preparations by the Government, will serve to corroborate and compound fears that their citizenship status might be further compromised in the future with the readier convenience of statute alone," the SDLP leader wrote.
