Demands were made in the House for an investigation into how key files on the 1970 Arms Trial had gone missing.

The prosecution file, the Garda investigation file, any working papers from which the book of evidence would have been constructed, transcripts and sound recordings of the trial are missing.

Labour's justice spokesman, Mr Brendan Howlin, called for an investigation into the disappearance of the documents, but he did not believe a formal inquiry into the events surrounding the Arms Trial would be a "useful exercise" for the Dail.

Fine Gael's justice spokesman, Mr Alan Shatter, said it was "scandalous that crucial and essential documentation relating to one of the major historical and political events should be unfindable".

Mr Caoimhghin O Caolain (SF, Cavan-Monaghan) said there was a cover-up, "and those documents were concealed or destroyed to serve that cover-up".

They were speaking during a series of statements to the House on the reports issued on Thursday by the Minister for Justice, the Attorney General and the Garda Commissioner.

The Government ordered the reports after an RTE Prime Time programme, which showed statements had been extensively edited to exclude implications that the then minister for defence, Mr Jim Gibbons, had known of and approved the plan to import arms.

The House earlier approved a motion allowing for the release of some of the documents withheld since a Public Accounts Committee investigation into the events of the early 1970s.

The Minister for Justice, Mr O'Donoghue, said the House would deal again with the reports in the autumn session. He had made inquiries about the missing documents and would report on the outcome when he received the answers.

The investigation that had been conducted was necessary because the allegations "question the integrity of the criminal justice system at that time". He was conscious of the serious implications for the reputation of a number of persons.

However, it was impossible on the basis of the evidence currently available to make an authoritative finding on the truth of the allegations. But based on analysis of the available material and other relevant considerations "it seems reasonable to infer that the likelihood of an attempt to suppress evidence is remote".

Evidence of any conspiracy to pervert the course of justice would be very unlikely to be recorded in documentary form.

His report could not reach definitive conclusions. It could be that definitive conclusions would never be possible. "Perhaps in this, as in so many other matters, history will have to be the best judge."

Mr Harry Blaney (Ind, Donegal North East) said the reports were of "crucial importance to the State and the well being of our democracy". Mr Blaney, brother of the late TD Mr Neil Blaney, the former minister acquitted in the Arms Trial, said: "Many noble, honourable and honest people had their lives wrecked, their careers ruined and their reputations impugned".