A new criminal offence of witness intimidation is to be introduced under the criminal justice legislation with a penalty of up to 10 years' imprisonment, according to the Minister for Justice.

During a 90-minute debate on the manslaughter convictions in the killing of Det Garda Jerry McCabe, Mr O'Donoghue also said the State would "vigorously resist" any legal action brought for the early release under the Belfast Agreement of those involved in his death.

Amid sharp criticism from the Opposition about acting on intimidation after the case rather than before the trial had started, the Minister outlined details of the planned legislation.

It would include allowing witnesses subject to intimidation to give evidence by video-link. In addition "we will make it an offence for people to try to trace witnesses who have been relocated as part of the witness protection programme", he said.

Stressing the Government's rejection of early release for those involved in the Adare ambush, the Minister said: "I wonder how many different ways we have to say `no' for people to get the message that those involved will not have the benefit of the early release terms contained in the Good Friday Agreement."

He said there had been "clarity from the outset" about this and the position had been made clear by himself and the Taoiseach. " The fact that there will now be manslaughter rather than murder convictions does not alter the Government's stance on this issue one iota."

The Release of Prisoners Commission established under the agreement could only consider cases specified by the Minister as "qualifying prisoners" and he did not regard the persons involved as "falling into that category so the question of referring their cases to the commission will not arise".

The deciding factor in accepting the manslaughter pleas was "professional judgment, honestly reached, and not any extraneous consideration". It was the prosecutors' professional judgment, that "in all the circumstances, the right course was to opt for the certainty of conviction, rather than run what was judged to be the unacceptable risk, if the murder charge were insisted upon, that the killers would walk free".

In terms of protecting witnesses liable to intimidation, he was advised by the Garda that "what the witnesses accepted was the maximum in terms of security arrangements they could be prevailed upon to accept".

Later during questions Mr O'Donoghue said it would be a matter for the Minister for Justice of the day to refer names to the Early Release Commission and he would not be referring those in the Det Garda McCabe case.

He was repeatedly questioned by a number of TDs about remarks made by the Sinn Fein leader, Mr Gerry Adams, on Radio Kerry yesterday in relation to his conversation with the Taoiseach about the early release of those convicted of killing Garda McCabe.

In his speech the Fine Gael leader, Mr John Bruton, had said Mr Adams was "effectively calling the Taoiseach a liar".

After renewed questioning by the deputy Labour leader, Mr Brendan Howlin, Mr O'Donoghue said he could "state categorically that I believe those statements to be false".

When he was asked by Fine Gael's finance spokesman, Mr Michael Noonan, whether the Adare killing was carried out by dissidents or approved by the IRA hierarchy, the Minister said he had no "concrete evidence" that it had the approval of the IRA hierarchy "though there does appear to be some information that the operation did have an involvement outside of those who were actually involved in Adare that day".

Mr Caoimhghin O Caolain (SF, Cavan-Monaghan) said there was "much genuine anger" about the case which was an "appalling event". The killing of Det McCabe was "wrong and abhorrent", he said, but he called for a full and open independent inquiry into allegations of ill-treatment of those questioned in connection with the case.

Mr Bruton said the huge efforts being made by senior members of Sinn Fein to have the men considered as eligible for early release suggested that the links between Sinn Fein and the IRA were still deep and strong. "As I said here last year, at the top level the direction of the two organisations is identical in philosophy, purpose and execution - they are one and the same. They are two organisations in one movement with one purpose, one strategy and one direction.

"Det Garda Jerry McCabe was murdered. Legalistic semantics do not alter that fact.

"On Radio Kerry this morning, the president of Sinn Fein, Gerry Adams, made alarming comments about the Taoiseach's remarks during the final hours of negotiating the Belfast Agreement. Mr Adams said that when he raised the issue of early release with the Taoiseach, the Taoiseach told him only that `it would be very difficult or words to that effect' and that `the Taoiseach didn't rule this out completely'. That is an alarming claim that must be immediately dealt with.

"These comments are very much at variance with his stance on this subject in recent days. He, and his successors, must stand firm. The Taoiseach must explain fully Mr Adams's account of their meeting in Belfast last Easter and tell us what he actually said."

The Fine Gael spokesman on justice, Mr Jim Higgins, said the compromise of accepting a manslaughter charge sent out all the wrong signals. "It is a clear indication that intimidation rules okay. It compromises the safety of the gardai by effectively stripping them of the protection and deterrent of a capital murder conviction."

Mr Howlin said he believed the Government had seriously misread the mood of the public regarding the extraordinary situation which lead to the DPP to accept please of guilty of manslaughter." The law may have taken its course, but justice has not been done."Is this the way the republican movement is going to repay the vote of trust society places in it by the early release of prisoners?"

He said the latest suggestions from Sinn Fein leaders that they might resort to the courts to try to support their contention that the killers were entitled to early release, was simply another example of the hypocrisy of the republican movement.

"On the one hand they are prepared to resort to the courts of this jurisdiction when it suits them: on the other hand those associated with the republican movement are willing to resort to the vile practice of threats and intimidation to pervert the course of justice and to prevent the members of their own organisation from being held to account in the way that the vast majority of our citizens wanted and expected."