The Ulster Unionist leader, Mr David Trimble, vigorously denied a "grossly offensive" allegation that he was involved in a conspiracy to murder Catholic and republican members of his constituency, he told the High Court in London yesterday.
The UUP MP for Upper Bann denied the claim, insisting there was "not a single scrap or shred of truth" in the allegation contained in a book called The Committee, written by a documentary film-maker, Mr Sean McPhilemy (52).
Mr Trimble was giving evidence for the Sunday Times in the fifth week of its defence of a libel action brought by Mr McPhilemy.
Mr McPhilemy is suing the Sunday Times over an article claiming his 1991 Channel 4 documentary, The Committee, was based on unsubstantiated rumours and lies provided by his main source, Mr Jim Sands, who has been described in court as a loyalist fanatic.
The Channel 4 programme alleged the existence of a committee of prominent Protestant businessmen, members of the security forces, loyalist paramilitaries, lawyers and politicians, who conspired to murder Catholics and republicans.
Mr McPhilemy later made a qualified withdrawal of an allegation in his 1998 book that Mr Trimble was "knowingly associating with and assisting" people responsible for the murder of his constituents in the late 1980s. However, Mr McPhilemy maintains that Mr Trimble was aware of the murder conspiracy and tried to cover it up.
Mr Andrew Caldecott QC, for the Sunday Times, referred to a passage from Mr McPhilemy's book, which was published in the US, in which he claimed Mr Trimble knew about the murder conspiracy and asked him if the allegations were true.
Mr Trimble said: "To say that I was knowingly associating with and assisting people responsible for the murder of my constituents is grossly offensive to me and would be extremely damaging but for the fact that I have not met anybody in Northern Ireland who takes this book seriously."
Mr Trimble revealed that he was suing in the jurisdiction of England and Wales the Internet bookseller, Amazon, over the publication of extracts of Mr McPhilemy's book on its Internet site.
Mr Caldecott then read out a note from the jury asking whether Mr Trimble's comments might only reflect the views of his "entourage". Mr Trimble insisted that it did not, but also the view of a London Labour MP who had told him that he believed Mr McPhilemy's book was "rubbish".
He also referred to detailed discussions he had had with the Sinn Fein president, Mr Gerry Adams, and the party's chief negotiator, Mr Martin McGuinness, and at no point had either mentioned the book or the allegations contained in it.
"If they believed it, I think they might very well have put them to me. These allegations have never been put to me by republicans in Northern Ireland," Mr Trimble said.
Under cross-examination by Mr James Price QC, for Mr McPhilemy, Mr Trimble referred to Mr Sands, the main source of Mr McPhilemy's documentary, saying he had never seen him or heard of him. He had not appeared in court "and that in itself tells a story," Mr Trimble said.
He also described the allegations contained in the documentary as "literally incredible" and said lives were placed at risk by Channel 4.