The High Court has been told the level of contact between gardaí and journalists during the Sophie Toscan du Plantier murder investigation was "beyond belief".

Lawyers for Ian Bailey told the court there had been an extraordinary level of communication of which they were not previously aware.

Mr Bailey is suing the garda authorities over their investigation into the murder of the French film-maker in 1996.

He was arrested twice in connection with the killing and has always denied any involvement.  He is seeking documents from the State to support his case against the gardaí.

Senior Counsel Martin Giblin told the court there had been developments in the case and they had received 12 boxes of documents.

They had also been informed in the past two days that there were transcripts of 130 tape recordings relating to the case but they had not yet had an opportunity to review them.

He said they had been transcribed in a very extensive operation which had been ongoing since February.

There were a large number of gardaí working on it, he said.

He said they would require an opportunity to inspect the material which was "entirely new to us, we were not aware of its existence". 

He added: "The defendants seem to suggest they were not aware of it but someone in An Garda Síochána knew about it."

He said they served a notice yesterday on the defence to inspect the material and would need an opportunity to follow that up.

Mr Giblin added there had been "an extraordinary level of communication between the gardaí and the media of which we were unaware.

"It is in the statement of claim that the media was used against the plaintiffs. The level of contact is beyond belief, we have a list involving hundreds of communications with journalists and we weren't aware the communication was of that nature.

"It seems the operation to retrieve that material is ongoing."

He said it seemed the defendants would not be asserting privilege over the material which would be helpful.

He also said they would be seeking urgent access to information disclosed to the Supreme Court nearly two years ago involving the identity of three senior gardaí named in a document before the court.

That will involved the DPP being asked to disclose the identity of the gardaí and may require a court order.

On RTÉ's Drivetime, Frank Buttimer, solicitor for Ian Bailey, said they became aware of the likely existence of material that was electronic in nature last November but it was only confirmed to him on Tuesday of this week.

He said that there appeared to be three strands to the tapes - communication internally between members of An Garda Siochana, external communication between the Gardaí and witnesses, and communication between the Gardaí and members of the media.

Mr Buttimer said the nature of the contact was extensive.

Senior Counsel for the State Paul O'Higgins consented to an adjournment of the case and said he would not be making replying submissions on the issues raised but added his silence should not be taken as agreement.

He said it would not seem likely the full hearing of the case would take place before the summer for a variety of reasons.

Mr Justice John Hedigan also issued a warning on the sub-judice rule and said the courts did not wish to restrict vigorous discussion by the media or the public of matters of great interest and importance.

However, he said a word of caution may be appropriate where that discussion involves matters that have been brought before the courts for determination and resolution.

"The sub-judice rule exists for the purpose of ensuring that parties who bring their case before the courts may have those cases heard and determined in the dispassionate and rational forum of the courtroom. It does not exist to stifle discussion of matters that may be involved in those cases," he said.

"Its purpose is to avoid any real or substantial risk of impeding or prejudicing  the course of justice in those proceedings. Both sides in the case and indeed the general public deserve no less.

"Commentary upon prejudgement of intended evidence not even produced before the court much less assessed by it is capable of impeding or prejudicing the course of justice in any proceedings and should be made with great care to avoid doing so," Justice Hedigan said.

"This warning is not aimed at the parties to this case nor to any particular group or person but is made generally with the aim of ensuring a fair trial of the issues that have been brought before this court for determination."

He said this was even more important given the case will be heard before a jury.

The case has been adjourned to 9 May but a full hearing will not take place before next November.