The judge in charge of the inquiry into taping at Garda stations has warned that 13 years of phone calls are stored in a format that will make them very difficult to analyse.

Justice Nial Fennelly says his job - to investigate the recording of all non-999 calls from 1980 onwards - is "extremely onerous and time-consuming".

The comments come in the second interim report from his inquiry, which was due to issue its final report before December 2015. 

However the judge has asked for a 9-month extension to his deadline, and also for more lawyers to help him in his work.

In particular that's because the calls from between 1995 and 2008 are held on tape - a format that makes it almost impossible to find recordings of calls between solicitors and their clients.

In fact from that period there are so many recordings, Justice Fennelly is STILL considering what kind of sampling system he could use, to get to grips with exactly what was recorded.

However there are no surviving recordings, of any sort, from before 1995 - while the recordings from after 2008 are all digital, making it much easier to search for records.

The Commission has built up a database of phone numbers from over 500 solicitors' firms, and is still in the process of matching those numbers against the database of recorded calls, to see exactly which clients and which cases might be implicated. 

Also ongoing is a specific investigation into the recording of phone calls from Bandon Garda Station, during the investigation into the murder of Sophie Toscan du Plantier. That strand will continue well into next year.