MR SEAN O'Callaghan - the former IRA terrorist turned Garda agent - is to appear in a United States court to testify against an ex-IRA prisoner fighting deportation proceedings.
The US authorities last night confirmed they had granted Mr O'Callaghan a visa, enabling him to begin a three-week tour of the US on Saturday. The former double agent told The Irish Times he would appear as a witness for the US authorities seeking the deportation of Tyrone man Mr Brian Pearson.
After serving 12 years of a 25-year sentence for possession of a bomb, Mr Pearson entered the US where he later married, without disclosing his conviction. He is one of seven men, previously convicted for paramilitary offences, currently facing deportation from the US.
In a recent letter to President Clinton, some 50 Congressmen claimed if they were deported "the men, because of their prior political activity in Ireland, will very likely be targeted for additional government harassment or paramilitary violence. Their families would also, be placed at considerable risk."
Mr O'Callaghan will make his New York court appearance next month, at the end of a four-city tour intended to challenge established US opinion about the Northern Ireland "peace process" and Sinn Fein's role in it. His high profile visit will begin in Washington with a dinner with the Ethics and Public Policy Centre and an appearance before the Senate Foreign Relations Committee.
News of his planned court appearance will fuel controversy over the granting of his visa so soon after his release from prison where he served eight years of two life sentences for the murders of UDR Greenfinch Eva Martin and Det Insp Peter Flanagan in 1974.
US sources yesterday insisted the visa decision was taken before the question of his possible court appearance arose and that the two events were coincidental.
The US Embassy in London supported Mr O'Callaghan's visa application. An official source yesterday said the decision was in no sense an endorsement of his views, but that it was felt right to let Americans "hear, question and challenge him" at first hand. It is understood the US Embassy in Dublin offered no view on the visa application.
Meanwhile the Irish Government - through its embassies in London and Washington - was accused of shunning Mr O'CalIaghan's US visit. It is understood the Irish Ambassador to London, Mr Ted Barrington, turned down an initial request for a briefing on Government policy preparatory to the trip.
However, an embassy spokeswoman last night said a formal request for a briefing was now "under consideration." Mr O'Callaghan was also awaiting a response from the Irish Ambassador in Washington, Mr Dermot Gallagher, who has been asked for a meeting to discuss the Irish-American dimension of the trip.
The historian and writer Ruth Dudley Edwards, who will accompany him, said she would be "amazed" if the embassies refused the requests: "This is a man who renounced violence and was a courageous servant of the state."
Mr O'Callaghan himself said officials were entitled to make their own decision, but he said they had been prepared to meet Sinn Fein leaders and "people with a history of loyalist paramilitary involvement" and that "as a citizen of the Republic I would have thought they would have granted me a meeting".
In any event, the stage is set for a highly public confrontation between Irish-America and the man who says "I don't believe for a minute that Gerry Adams and Martin McGuiness will abandon the option of violence unless it is taken from them."
The finale will come in a New York courtroom, where Mr O'Callaghan will find himself under questioning from Mr Pearson's defence attorney - the former Noraid leader, Mr Martin Galvin.