The Ulster Unionist leader, Mr David Trimble, has said the British government must declare the Provisional IRA's ceasefire is over the next time the organisation carries out a murder.
The Northern Secretary, Dr John Reid, would have to treat the Provisional IRA in the same way it had treated the UDA and the LVF if it carried out any more gun attacks, he said.
"The next time the IRA murders someone, Dr Reid must take exactly the same action he took against the loyalist groups. Over the course of the last year, the IRA has murdered four people and nothing has been done about it. Dr Reid won't want to look as though he is being biased in his approach."
Mr Trimble said the UUP would be compiling a dossier of Provisional IRA activities. "I will be very firm on this and Dr Reid will be made aware of every IRA attack that takes place. He won't be left in any doubt about what they are doing."
Mr Trimble is currently in Washington where he is meeting key political figures including the US Special Envoy, Mr Richard Haas. He will return to the North on Wednesday when the withdrawal of his three ministers from the Executive is expected to begin if Provisional IRA decommissioning has not started.
Mr Trimble said he would be making a more detailed statement outlining his plans today.
If the resignations happened, Dr Reid would have no choice but to suspend the political institutions.
"It is inevitable, given the failure of the republican movement to demonstrate a commitment to exclusively peaceful means and its failure to decommission," he added.
Sinn Fein MP Mr Martin McGuinness said he was working "flat out" to convince the IRA to give up its weapons.
While the Executive's suspension would mark the end of the Belfast Agreement, it wouldn't represent the end of the peace process.
He would not say if a move on arms could happen in time to prevent suspension.
"I want to see arms put beyond use. I want to see it this afternoon, tomorrow morning. I'm working flat out to try and achieve that," he told BBC Radio Ulster yesterday. "If the British government suspends the institutions and we go into a review, many people will be of a view that it will be highly unlikely that we will see those institutions re-established.
"It could herald the end of the Good Friday agreement but should not necessarily herald the end of the peace process.
"All of us need to continue to work to achieve peace on this island," Mr McGuinness added. "I certainly am one of those people in republicanism who want to live in peace with our unionist neighbours."