The Minister of State for Justice, Ms Mary Wallace, strongly denied that the Government was interfering in the investigation into the Omagh bombing.

Ms Wallace stressed the Government's "unswerving commitment" to bring those responsible to justice. "No government could have any greater commitment."

She added she could not ignore reports in certain parts of the media that the Government had, in some way, been putting political pressure on the Garda with the intention of interfering with the investigation.

"The details of the allegation, such as they are, are so preposterous as not to be worth repeating, and I simply reject them with contempt. I would ask the House to do likewise. This monstrous allegation can only cause hurt to those who lost loved ones in Omagh and to the survivors of that terrible atrocity, and generate suspicion and distrust."

She asked deputies "not to breathe life into this contemptible story by saying anything which would be open to the interpretation that they believed it could possibly be true".

Ms Wallace was replying to a Fine Gael private members' motion calling on the Government to outline what action had been taken on foot of the enactment of the Offences Against the State (Amendment) Act, 1998, details of further measures being considered, and the discussions which had taken place between the Irish and British governments on the matter.

The motion also calls on all deputies to support the call by the Taoiseach and the British Prime Minister for the public to assist the authorities with any information which might help to apprehend those responsible for the bombing.

Ms Wallace said the Government would accept the motion, which will be debated tonight. She added that the commitment of the Garda and the Government to bringing the Omagh bombers to justice was beyond question.

Outlining the terms of the Offences Against the State (Amendment) Act, she said it was not the Government's function to enforce it. It was for the Garda and the courts to apply its provisions in appropriate cases, but it was quite right, however, that the House should keep its operation under review.

The Fine Gael leader, Mr John Bruton, said the Omagh bombing was the greatest single crime committed in Ireland during the last 200 years. Yet, so far, despite the extended powers given to the Garda, not a single person had been convicted in connection with the atrocity.

Two years ago, after Omagh, the Taoiseach had promised that the perpetrators would be locked up for a long time. The so-called "Real IRA" could not hope to take on the people of Ireland and win, he had said. At the same time the Minister for Justice got the Dail to agree on (the legislation) to overturn the rules of evidence to facilitate prosecutions for membership of an illegal organisation. "If the identities of the Omagh bombers are known, as The Irish Times says, why have these new powers not been used?"

Questions in relation to the Omagh bombing had been raised by journalists in recent days - by Jim Cusack in The Irish Times and Henry McDonald in the Observer. Did the Minister for Justice believe that such questions were designed to "destabilise the peace process", as a Government spokesman had put it? In any event, the Dail was the place to ask such questions, Mr Bruton insisted.

He called for the use of "accomplice evidence" by the Garda in relation to Omagh, as in the Veronica Guerin murder case. Despite any apparent political sensitivities that might be thought by some to exist in the matter of collaboration with the RUC he believed this to be the proper course.

Mr Brian Hayes (FG, Dublin South West) said last week's BBC Panorama programme had unleashed an understandable public reaction throughout the country in relation to Omagh. There were some who would prefer that the entire matter should be forgotten or ignored. "These are the same group of people who are worried about how increased pressure could lead to a further splintering of the republican movement."

Mr Austin Currie (FG, Dublin West) said that if a choice had to be made between a power-sharing Executive and an acceptable police service in the North, there was only one answer. A police service acceptable to both communities had to be the choice.