GSOC chairman Simon O’Brien also said he would be staying in his post after a Government-commissioned report found no evidence to support concerns the agency may have been bugged.
His comments came after a retired judge found that evidence did not support the proposition that surveillance of GSOC took place or that it was carried out by gardaí.
It studied three “threats” to GSOC’s security at its Dublin offices which were previously identified by a private British security firm. These included links to an external wifi system, a UK mobile-phone network operating in the area, and concerns that an office phone was bugged.
John Cooke found the first threat as “highly improbable and “implausible” while the second may have been down to a mobile-phone network testing in the area.
But on the third point, which centred around a mysterious ‘ring-back’ on a phone when it was tested by investigators, the judge said it remained “unexplained as a technical or scientific anomaly”.
Mr O’Brien yesterday said questions remained about the third “threat”.
“We still have an outstanding matter that is unexplained and on that basis we cannot say that we would not be under surveillance of any kind,” he said.
The report concluded that the “range of technologies and devices available for the conduct of remotely sourced and untraceable eavesdropping or interception of different forms of communication is such that it is difficult categorically to exclude the possibility that some form of illicit eavesdropping may have taken place”.
Mr O’Brien defended GSOC’s original decision to commission its own investigation last year into suspicions it was bugged.
Speaking to RTÉ, he said: “We work with evidence, we came to our conclusions, we properly investigated credible threats, and we closed our investigation and that is very similar to where the judge has got himself to after another four months.”
Asked if his position was untenable, Mr O’Brien said: “I don’t think my position is untenable at all.”