THE Ulster Unionist leader, Mr David Trimble, said yesterday that any parties which came to negotiations on June 10th in a Northern Ireland forum would be "out the door immediately" if they did not agree to the Mitchell principles.
He also warned that there would be no negotiations with Sinn Fein if violence such as punishment beatings continued.
"If Sinn Fein feel they can pull the trick that they pulled at the end of last year and carry on the murders and beatings through other names such as the Direct Action Against Drugs (DAAD) it's not going to work," he said.
Sinn Fein has denied any connection with DAAD, which is widely believed to have been a cover name for the IRA.
Mr Trimble is in Washington for St Patrick's week events. He had consultations with White House officials yesterday afternoon.
The SDLP leader, Mr John Hume and the Alliance leader Dr John Alderdice, had separate meetings with the US national security adviser, Mr Tony Lake, in the White House.
Up to late yesterday no details had emerged of an anticipated meeting between officials and Mr Gerry Adams outside the White House, from which the Sinn Fein leader is excluded because of the end of the IRA ceasefire.
Mr Hume is believed to be anxious to win White House support for the list system of voting in Northern Ireland, so that the paramilitary groups would be represented at negotiations.
Mr Trimble told a press conference in the National Press Club that he envisaged a twin track process in the elected body in Northern Ireland after June 10th.
"One track will be an elected body in the form of a convention, the other track will be the actual negotiations," he said. "For any party to take part in negotiations they must not be engaged in violence," he said.
"There must be a ceasefire. If there is no ceasefire then political parties relating to those paramilitary groups simply don't get over the door.
"All participants would need to make clear at the beginning of the discussions their total and absolute commitment to the principles of democracy and nonviolence set out in the report of the international body of Senator Mitchell."
The Mitchell Principles call for the use of peaceful and democratic means to resolve problems; total disarmament; independent verification; renunciation of force, or threat of force, to influence the outcome of negotiations; abiding by any agreement reached and the use of peaceful methods to alter disagreements; and an end to punishment killings and beatings.
"So you have to have a ceasefire to get over the door. Once you get over the door, then immediately there is the Mitchell report."
The parties must sign up to the whole report "and all that implies," he said. "And the Mitchell report implies a continuing course of conduct. It's not just a matter of making a declaration and that's it.
"If a party enters into negotiations and then doesn't act in accordance with the principles in the Mitchell report, then they're out. So once you get in, sign up to Mitchell, act in accordance with Mitchell. That sets some very stiff tests for the paramilitaries, all of them, not just Sinn Fein."
Mr Trimble said he did not see much prospect of Sinn Fein signing up to the Mitchell report or acting in accordance with it.
"The communique of the two governments only really makes sense on the basis of its willingness and determination by the two governments and the other parties to proceed without Sinn Fein," he said.
"If Sinn Fein is not there and the violence continues then there is a very clear obligation on the governments to respond, and that obligation lies heaviest on the Irish government as the IRA bombing campaign operated out of the Irish Republic," he said.