The deputy leader of the SDLP, Mr Seamus Mallon, has warned of dire consequences if the Belfast Agreement collapses, with the possibility of dangerous unrest and the stalling of the political process for a long time if the review into the implementation of the accord fails.
The Newry and Armagh MP yesterday stressed the "horrendous" repercussions, if the British and Irish governments seize control over Northern Ireland's affairs and a political vacuum is created in the North.
Mr Mallon said failure would "set back the political process here not just for years, but for decades, and create the type of unrest and unease within the community that could be very dangerous of itself.
"If we do leave that void, then I'm afraid we're leaving the door open to others who are going to try and make things happen in their terms, in their own way - a way none of us want and none of us like," he added.
Mr Mallon, who resigned as the North's deputy First Minister in July after the failure to set up a power-sharing executive, said many of the progressive steps already achieved through the process would be jeopardised.
"It would mean unionism, as is represented by their political parties, would have failed to make the necessary adjustments as defined in the agreement which alone can provide the basis for a new stable political dispensation here."
Mr Ian Paisley jnr of the Democratic Unionist Party reacted angrily to Mr Mallon's comments, describing them as "a threat" and demanded they be withdrawn because "he cannot hold the public to ransom".
"The threats come from a party that has shared the company of Sinn Fein/IRA for too long. Such threats demonstrate that the Belfast Agreement is in place because of violence and threat of a return to violence," he added.
The DUP also accused Mr Mallon of "missing the point". DUP Assembly member, Mr Nigel Dodds, said there was already a totally unacceptable level of violence across Northern Ireland but the pro-agreement parties were turning a blind eye to it.
"Seamus Mallon fails to address the real problem with the Agreement. It is not the failure to implement it, it is the fact that it does not enjoy the support of the majority of the unionist community and can never hope to do so," said Mr Dodds.
The deputy leader of the Ulster Unionist Party, Mr John Taylor, said yesterday he had "no doubt" that over 75 per cent of Protestants now reject the Belfast Agreement.
"It is no good supporters waving posters to say that over 70 per cent supported the agreement. That is history. Today at least half of the Protestants who voted `Yes' would now vote `No', said the Strangford MP who effectively defected to the anti-agreement wing of the party in recent weeks. He has also refused to join his party's negotiating team in the review. Mr Taylor blamed Sinn Fein for the failure to set up an executive because of the party's refusal to commit itself to exclusively peaceful and democratic means and said there was total agreement within the Ulster Unionist Party over the policy of "no guns - no government".
"There is no split in the party on policy. "There is, however, a difference of opinion about tactics," he added. Meanwhile, the Workers' Party called on the North's politicians to show "compromise and political courage".
The party's Belfast chairman, Mr John Lowry, said the community had invested too much in the Belfast Agreement to allow "party antagonisms, tribal intransigence or publicity gimmicks to scuttle the whole process".