The Sinn Fein TD for Cavan-Monaghan, Mr Caoimhghin O Caolain, has warned he could not support any changes to Articles 2 and 3 of the Constitution which would detract from Irish sovereignty.
Speaking at an Easter 1916 commemorative event yesterday in Glasnevin Cemetery in Dublin, he said he would reserve judgment on the Northern Ireland peace agreement until the party's negotiating team had presented its assessment to members.
However, he said: "I would be opposed to any dilution or diminution of Articles 2 and 3. I would be also opposed to the inclusion of what I would read to be a unionist veto.
"I have to defer making a full judgment on the formula of words that are presented until we have the opportunity as a party to make a proper determination. But certainly these are concerns that republicans are going to have to face and make a judgment on very, very soon."
Mr O Caolain assured a crowd of about 600 people who walked from O'Connell Street to Glasnevin that the peace talks were a new phase in the struggle to end partition.
"The only final settlement between Britain and Ireland, and among the people who share this island, can be on the basis of national self-determination for the Irish people." He said the peace agreement "must not block or delay the achievement of the national objective. On the contrary, it must be a definite transition from the injustice of partition to the justice of Irish unity and sovereignty."
In relation to the agreement, he paid special tribute to the IRA and republican prisoners. "The IRA, the successors of the men and women of 1916, have made the greatest efforts in the struggle for Irish independence. They have played a central role in the creation of the opportunity to achieve lasting peace with justice though a negotiated settlement. I commend their initiative, their patience and their tenacity."
On the issue of prisoners, he said he deplored "the continuation of extradition of people charged with political offences from this jurisdiction to Britain and the six counties".
Wreathes from the IRA, Sinn Fein and local branches of the party were laid at the republican plot in Glasnevin.
Earlier, a short pageant of music and song was held outside the GPO. Speeches were given recalling "six generations of struggle" from the 1798 Rebellion to the present day.
