The Special Criminal Court has adjourned a trial to allow time for defence lawyers to consider requesting an independent expert assessment of two Tipperary garda stations in light of the recent revelations about the recording of phone calls.

However, the court has ruled that the trial of two Limerick men accused of IRA membership should proceed.

The court ruled it had heard "positive" and "impressive" evidence that neither of the two garda stations involved in the case were part of the systematic recording of telephone calls.

More details emerged this afternoon to the court of the systematic recording of calls in garda stations.

The court heard evidence from a superintendent in the telecommunications section of An Garda Síochána who is carrying out a review of the system.

Supt Michael Flynn told the court a system was in place in 23 stations outside Dublin, which were divisional headquarters, and at Harcourt Square and Garda Headquarters.

He said the system dated back to 1996 and was upgraded in 2008.

He said the system was centrally controlled at Garda Headquarters and was switched off last November.

The contents of calls were stored centrally but could be accessed locally on the instruction of a chief superintendent.

Supt Flynn said an interface unit was installed in certain stations and connected to designated extensions. It uploaded the contents calls to a central storage device at Garda HQ.  

He said he was carrying out a review of the system which was ordered 48 hours ago and was ongoing. However he said there were "also some inquiries" made before that.

Supt Flynn said two Tipperary stations at Cahir and Clonmel at the centre of the case currently before the Special Criminal Court were not involved.

Prosecuting barristers said calls were not recorded in the stations where two men accused of IRA membership were detained and the trial should proceed.

Defence lawyers had objected to the trial going ahead without further information on whether or not their clients' phone calls from garda stations had been taped.

Thomas McMahon, 31, of Ross Fearna Murroe and his co-accused 34-year-old Noel Noonan of St Patrick's Hostel, Clare Street in Limerick were due to stand trial yesterday for membership of the IRA.

Defence counsel Isobel Kennedy had earlier urged the court not to embark on its own inquiry in advance of the inquiry announced by the Government.

After hearing evidence from Supt Flynn she said there was no physical examination of the garda stations involved and rejected  the prosecution's contention that there was "clear physical evidence" that no recordings have taken place.

She said her client had instructed her that an independent expert examination of the stations in question be carried out.

Mr Justice Butler said he had heard first hand and impressive evidence from Supt Flynn.

He said "of course there can be recordings anywhere but what we are dealing with is the allegation of systematic recording of telecommunications".

He said "in our view the case should go on". However he said he would give the defence an opportunity to consider if they want to have a physical inspection of the two stations by an expert.

The case was adjourned to next Tuesday.

At the outset of today's hearing, Mr Justice Butler said the High Court President had issued guidance this morning to courts dealing with such issues and said the court should seek clarification and information from the prosecution and allow defence lawyers time to respond.

He said the primary concern of the High Court President was the proper administration of justice.