Sinn Féin has accused the Government of not being vocal and assertive enough in ensuring that the British government honours its commitments under the Belfast Agreement.
Delivering the annual Ferghal O'Hanlon lecture in Monaghan yesterday, Belfast's Lord Mayor, Mr Alex Maskey, also criticised the Government's record on policing in the North, paramilitary prisoners and all-Ireland institutions.
The Government had a heavy responsibility to shoulder, he said. "The Irish Government are joint co-equal partners with the British government in the shaping and protection of the agreement. They have a joint co-equal responsibility for its implementation.
"They also have an onerous responsibility to promote and defend Irish national interests and the rights of all Irish citizens living in the Six Counties.
"It is my view that there have been a number of occasions in the last few years when they should have been more vocal and assertive in ensuring that the British government honoured their commitments.
"I believe this is particularly relevant in at least two crucial areas: the development of the all-Ireland institutions and the implementation of the Patten recommendations on policing."
Mr Maskey said that the all-Ireland institutions were a "pale reflection" of the Assembly and the Executive. Yet these were the institutions nationalists were most keen to see developed to the maximum.
Sinn Féin expected the Government to use its "considerable resources" to advance these institutions, but it had failed to do so. The Government had also been "found wanting" on policing, he added.
Nationalist unity on the full implementation of the Patten recommendations had been needed to pressurise the British government, Mr Maskey said. He accused the Government of failing to honour its commitment to the release of all paramilitary prisoners. "They have no justification for the continuing imprisonment of those republicans in Castlerea Prison. They should be released immediately."
Mr Maskey said that the primary responsibility for the failure to implement the Belfast Agreement, five years after its signing, lay with the British government.
"Anti-agreement elements inside the British government and the unionist parties are setting the agenda. They have filtered the proposed changes through a unionist view of the world.
"The dead hand of these forces has held back the pace and the extent of the changes promised in the Good Friday agreement."
Mr Maskey insisted that the failure to implement the Belfast Agreement did not invalidate the agreement. The agreement was a "clear recognition" of the fact that partition had failed, he claimed. A new police service which nationalists could support and join, transparent legislation on justice and human rights, and parity of esteem for cultural rights were needed, he said.
The recently released British Cabinet papers of 1972 on repartition showed the "absurd and shallow nature" of London's thinking and policy and highlighted the colonial nature of the problem.
A form of "hidden partition" was still occurring in the North, he said. Nationalists living along the peace-line in north and east Belfast, and in Antrim, north Armagh and north Down, were being intimidated from their homes.
A "blind-eye approach" by the British military authorities left nationalists "vulnerable and uncertain about where to live in their own country".
The Belfast Agreement offered everyone a peaceful future, equality and an opportunity to reshape Irish politics, he said.
"I am satisfied that with the proper will on all sides it can not only withstand the pressures of this year, it can grow in strength and prove for the first time in centuries that the people of this island and Britain can work out their difficulties peacefully and politically."