The Irish Secretary of the National Union of Journalists has said he is concerned that GSOC is able to access the mobile phone records of journalists without informing them in advance.
The Garda Ombudsman has used new powers given to it last year to access the phone records of two journalists as part of its investigation into information leaked about the death of model Katy French.
Speaking on RTÉ's Morning Ireland, NUJ Secretary Seamus Dooley said there was a veil of secrecy around ongoing investigations and he will be seeking a meeting with GSOC about the matter.
He said that while GSOC was established for very good reasons of greater transparency and garda accountability, it was also important the media operate in a free, open way and that their sources are protected.
Mr Dooley said that modern mobile phones stored more than phone numbers. People will think twice about talking to journalists if they feel they are going to be subject to an investigation of this type, he said.
"This is not a question of GSOC trawling through a few phone numbers. Your mobile phone is like a mini computer and it stores meta-data," he said.
"The notion that without any access to a court that GSOC can go in and secretly, without the knowledge of the journalist, and get this is information is very worrying."