The Ulster Unionist Party leader, Mr David Trimble, has called for the replacement of the Anglo-Irish Agreement, saying that it had failed in its basic objectives of bringing peace, reconciliation and stability to Northern Ireland.
He said he believed the only way to bring this about was by "positive involvement in the political process".
In a clear reference to the DUP's withdrawal from talks, Mr Trimble said: "We are not going to get this replaced by adopting an abstentionist policy."
Speaking at the Northern Ireland Forum for Political Dialogue in Belfast yesterday, he called on the British government to recognise that the Agreement, which was signed 12 years ago today, had failed because it was based on "complete misunderstandings and complete falsehoods".
Mr Trimble went on to claim that a statement in the Anglo-Irish Agreement saying that it did not affect sovereignty was false. "It does involve a substantial diminution of British sovereignty over Northern Ireland."
As a result of the Agreement, democratic rights had been diminished because powers had been given to the Irish Government which was not accountable to the people.
Mr Trimble said documents leaked during the presidential campaign had been "a reminder of how far that influence goes", as an Irish Government official was consulting a member of the SDLP over public appointments.
The Northern Secretary, Dr Mo Mowlam, had told him that the Irish Government was only informed of vacancies and not of candidates for public appointments, thus it could not comment on candidates applying from other sources. Dr Mowlam also indicated that candidates, from whatever source, were all required to go through the same process.
Mr Trimble said he believed that there was nothing in Dr Mowlam's reply to indicate that the influence of the Anglo-Irish secretariat was excluded. This system was also giving "a favoured position" to the SDLP, he said.
The UUP leader said that any replacement of the Anglo-Irish Agreement would have to involve "significant change" to the Constitution, in relation to the claim over Northern Ireland in Articles Two and Three. Both the Agreement and the Framework Document of 1995 had failed on the issue of consent, he said.
The UUP wanted a replacement "which looks at the totality of relationships within the British Isles as a whole".
Mr Peter Robinson of the DUP supported the motion, saying he was still "just as angry and just as resentful" at the actions of the British government in signing the Agreement as he was 12 years ago. He said the Anglo-Irish Agreement and subsequent agreements between the British and Irish governments had the clear intention of steering Northern Ireland into a united Ireland. The Alliance Party leader, Lord Alderdice, said he did not believe that people generally felt the same depth of fear or anger over the Agreement that they had felt 12 years ago.