The republican party's chief negotiator, Martin McGuinness, made the warning in response to demands that the IRA hand over its weapons before Sinn Fein is allowed to take seats in the new Northern Ireland Assembly.

Unionist leader and Northern Ireland Assembly First Minister, David Trimble, called on UK Prime Minister Tony Blair to honour a promise that arms decommissioning will start before Sinn Fein can join a Stormont cabinet.

His comments were endorsed at the Ulster Unionist Party conference on Saturday.

Unionists criticised

McGuinness: Trimble taking 'unilateral decision'

Mr McGuinness accused David Trimble of succumbing to "rejectionist unionists" by backing their demands for republicans to disarm before joining the power-sharing executive.

Mr McGuinness complained that Mr Trimble had taken a "unilateral decision" to demand decommissioning.

He said the peace deal stated that the assembly executive and a north-south ministerial council should be set up by 31 October without the necessity for disarmament.

Mr McGuinness restated Sinn Fein's commitment to the agreement but added: "David Trimble is attempting to take all powers from the assembly, which was elected democratically, and hold everything for himself and to take unilateral decisions which I think are undoubtedly going in the coming weeks and months to poison the entire atmosphere."

Sinn Fein 'propaganda'

Maginnis: Need for commitment to non-violence

Ulster Unionist security spokesman Ken Maginnis accused Mr McGuinness of "propaganda".

"He does not deal realistically with the agreement," he said.

"Ulster unionism has bent over backwards to accommodate and bring in from the cold those people who for 30 years have been our sworn enemies."

He warned that unless "extremes" failed to recognise social and moral arguments "it's going to be extremely difficult".

Mr Maginnis denied that unionists were distorting the agreement.

"If you read the agreement as a whole it makes it very clear that any party that's going to take its place within the devolved government within Northern Ireland has to be wholly and tangibly committed to non-violence," he said.