The TD who first raised allegations about SiteServ said she was warned her own phone could be under surveillance.

Catherine Murphy and an assistant resorted to using so-called "burner" phones in order to contact their sources.

Much of the information brought forward by Deputy Murphy at the time of the SiteServ controversy last year was received from confidential sources.

The Communications minister says anyone who suspects their phone is being tapped should contact their phone operator - and then the Gardaí.

However one expert in the legal area says Gardaí themselves are able to initiate the surveillance of a person's phone records - without any kind of political oversight and without the subject ever being made aware.

Meanwhile the Sinn Féin president Gerry Adams has said he has always operated on the basis that his phone is under surveillance.

Our political correspondent Gavan Reilly reports.