The Ulster Unionist Party today pulled out of talks in Belfast seeking to restore devolved government to Northern Ireland.
Party leader Mr David Trimble said the British government's failure to exclude Sinn Fein from the talks reviewing the workings of the Belfast Agreement following the alleged abduction of dissident republican Mr Bobby Tohill was "quite appalling".
Mr Trimble added: "We have to show to paramilitaries our government will not tolerate such blatant breaches of the peace,"
Despite withdrawing from the review talks, Mr Trimble said the UUP would continue to talk to other parties about the general political situation.
David Trimble
Mr Trimble has been threatening to pull out of the talks for several days and is due to meet British Prime Minister Mr Tony Blair in Downing Street tomorrow to discuss the Tohill affair and Sinn Fein's continued involvement in the review talks.
Several people have been charged in connection with the alleged abduction which, within hours of it happening, Chief Constable Hugh Orde blamed on the Provisional IRA.
The Trimble withdrawal came as Irish and British ministers met the parties in Belfast in the latest round of review talks. There was one issue on the agenda - continuing paramilitary activity.
It is the single issue which has been overshadowing the review, launched with the aim of putting power back in the hands of the locally elected politicians.
Northern Secretary Mr Paul Murphy and the Minister for Arts, Sports and Tourism, Mr O'Donoghue, leading the discussions with the parties.
Mr Trimble announced his withdrawal after discussions with the two ministers. He said he had pressed for action against Sinn Fein.
Mr Murphy and Mr O'Donoghue had listened "but they said they are not in a position to respond to the particular requests that we have put.
"So consequently, we are taking matters further. I and my colleagues will go tomorrow to see the Prime Minister."
He said that until they get a positive response on the issue "we are not going to participated further" in the review talks.
Sinn Fein assembly member Ms Bairbre de Brun said: "Unionist leaders need to accept their responsibility to use their influence to bring an end to sectarian attacks on Catholics emanating from their community."
She said: "The reality is that the IRA poses no threat to the peace process."