The Rev Ian Paisley today led Democratic Unionist MLAs out of the Northern Ireland Assembly after accusing the British government of double standards.
Rev Paisley claimed a republican and nationalist coalition was now in operation.
The North Antrim MP said that if either the SDLP or Sinn F[AC]ein had resigned from their posts the cabinet would have collapsed.
"Today no self-respecting unionist can remain in this chamber and pretend that we can do business with a government that is both republican and nationalist."
After he left, Ulster Unionist leader Mr David Trimble called on Secretary of State Mr John Reid to take urgent action to resolve the political crisis.
Speculation is mounting that the IRA is on the verge of an historic move on decommissioning.
But Mr Trimble said: "We are in a very difficult position here in a situation where there are five vacant ministries with immediate implications of what can be done and what can't be done.
"Dr Paisley's party followed Ulster Unionists into the executive, they followed Ulster Unionists on to the policing board, they followed Ulster Unionists when they withdrew and I'm sure they'll follow Ulster Unionists when we go back," he said.
Outside the chamber Sinn Féin deputy chief whip Mr Conor Murphy called on unionists to stop engaging in stunts.
"Obviously the unionists are trying to outdo each other in walking away from the institutions. There seems to be competition between them as to who can walk away most quickly.
"The outstanding issues in the Agreement won't be resolved by people walking out. They will only be resolved by people staying in the Assembly and the Executive and working through the problems.
PA