The allegations by a former US ambassador to London that the White House passed confidential British security information to the IRA are "not worthy of comment", Mr Tony Lake, the head of the National Security Council staff at the time, said last night.
Mr Lake, who is now a professor in Georgetown University, was the most senior White House official dealing with Ireland at that stage.
Congressman Peter King, a Republican member of the International Relations Committee of the US Congress, said yesterday that it was "absolutely disgraceful" for Mr Raymond Seitz, who was US ambassador to London from 1991 to 1994, to make such charges without revealing any foundation for them.
He said he would be asking the committee chairman, Mr Ben Gilman, for an investigation into what he called charges of "almost treason" against former National Security Council officials Mr Lake, and his assistant, Ms Nancy Soderberg.
The US ambassador to Ireland, Mrs Jean Kennedy Smith, has also criticised Mr Seitz, describing comments he made about her in his memoirs as "unfortunate". Mr Seitz, in an extract from the book, had said she was "an ardent IRA apologist".
Ms Soderberg, who is now a high-ranking official at the US mission to the United Nations in New York, with ambassadorial status, did not want to comment on the charges when reached in her office yesterday. She has not yet seen the extracts from Mr Seitz's book published at the weekend in the Sunday Telegraph, in which she is described as "a dedicated Adams advocate".
The White House is refusing to comment on what it calls the "intelligence matters" in Mr Seitz's book. A spokesman said that President Clinton has "full confidence" in Mrs Kennedy Smith.
It is not clear if Mr Seitz submitted his book to the State Department for clearance concerning confidential or classified material he might have used. It is understood that neither Mr Lake nor Ms Soderberg was informed by the State Department that a former ambassador was making serious charges against them.
Mr King said yesterday that he was not sure if Mr Seitz had to submit his book in advance to the State Department. But "morally he should have".
He said: "Look what he is doing. The peace process is in a crisis right now and there have been a number of people killed in the last few weeks. For him - Mr Seitz - to be coming out with this is undermining the peace process. He is appealing to the worst fears of the right wing in Britain."
Mr Seitz was also undermining President Clinton, the UK Prime Minister, Mr Tony Blair, the Taoiseach, Mr Ahern, and the Sinn Fein president, Mr Gerry Adams, Mr King said. "That a former high-ranking US official can do this is to me absolutely disgraceful." Mr Seitz was "taking a diplomatic difference and almost implying treason by secret agents in the White House".
Mr King said that "you would never find any respectable member of the British government claiming that secrets were leaked" from the White House. "Certainly the British embassy in Washington has never said that, and I deal with them all the time."
He pointed out that Ms Soderberg has been a frequent guest at British embassy dinners. At a dinner last year to mark the departure of the political officer dealing with Northern Ireland matters, Ms Soderberg was invited to be a speaker.
When Dr Mo Mowlam came to Washington on her first visit last year, Ms Soderberg was sitting at the same table at an embassy dinner in the Northern Secretary's honour.
Kennedy Smith's statement; Seitz profile: page 8