DUP leader Ian Paisley has said the general election results had seen the burial of the "so-called agreement".
The DUP's nine MPs were being sworn in at Westminster
Mr Paisley was speaking outside the House of Commons, where he and the party's other eight MPs will be sworn in on Thursday.
He warned new NI Secretary Peter Hain to "heed the ballot box and listen to what the people of Ulster are saying".
Mr Paisley said if the secretary of state's intention was to confront the unionist people he would fail.
He added that the DUP "would not be talking to the IRA now, tomorrow or ever".
Mr Paisley said his first priority would be to ensure fair DUP representation on all boards in Northern Ireland.
This would ensure the people of Northern Ireland had "independent Ulstermen representing them, not paid government lackeys," he said.
Most of Northern Ireland's new MPs will be sworn in at the House of Commons on Thursday.
The DUP flew to London on Tuesday in larger numbers than ever before - its parliamentary team has grown from six to nine.
While William McCrea has been an MP before, new to Westminster are Sammy Wilson and David Simpson.
Mr Simpson said the DUP will be working to ensure that local issues remain high on the agenda.
While Sinn Fein's five MPs do not take their seats at Westminster, both Pat Doherty and Conor Murphy travelled to Westminster on Wednesday to use facilities there.
Mr Murphy said: "Sinn Fein fought hard to secure the use of our facilities at Westminster in line with our substantial electoral mandate.
"In the years since, we have used these facilities both to deliver for our constituents and also to advance the peace process and the united Ireland agenda."
Three SDLP MPs have also gone to the Commons.
Eddie McGrady has now be joined by party leader Mark Durkan and Alasdair McDonnell, rather than long-time MPs John Hume and Seamus Mallon.
Lady Sylvia Hermon will be the lone representative of the Ulster Unionists in the Commons, after the party lost four seats in the general election.