The former chief executive of the Road Safety Authority was told by the then Garda press officer Superintendent David Taylor that his phone could be monitored, the Charleton Tribunal has heard.
Noel Brett told the tribunal that he was later assured by then Commissioner Nóirín O'Sullivan that he was not on a list of intercepted phones.
Mr Brett said that in 2012, Conor Faughnan of the AA passed on to him information about irregularities with penalty points. He said he later met with whistleblower Sergeant Maurice McCabe about the issue and contacted the Comptroller and Auditor General, and GSOC as a result.
The tribunal is looking at allegations that senior gardaí were smearing Sgt McCabe to politicians, journalists and others.
Mr Brett said that on one occasion he and RSA chairman Gay Byrne had to walk out of a meeting with former Garda Commissioner Martin Callinan that had become heated. He said that Sgt McCabe was not discussed during this meeting, which covered road safety issues.
Mr Brett said that there were rumours circulating about Sgt McCabe, and "you'd hear it in the civil service, you'd hear it from media people. It was as vague as "you can't trust him, he's got issues"."
Mr Brett said that he told then transport minister Leo Varadkar that there were rumours about Sgt McCabe. He said he did not hear the rumours from garda members.
Solicitor Gerald Kean told the tribunal that statements made on the Marian Finucane RTE radio programme on Sunday 26 January 2014 were based on information he got from former Garda Commissioner Martin Callinan.
Mr Kean was cross-examined by Micheál P O'Higgins, who represents an Garda Síochána and Mr Callinan.
Mr O'Higgins said his client had "a clear view" that Sgt McCabe had failed to avail of an opportunity to co-operate with the O'Mahoney internal Garda inquiry into his complaints.
Mr O'Higgins also said it was Mr Callinan's position that he did not tell Mr Kean not to mention his name, and that he only discussed facts in the public domain.
"No, that's simply incorrect," Mr Kean said.
Mr Kean said that he would have loved to have been able to say during the broadcast that his information came to him from the Garda commissioner. "I would have loved that opportunity," he said.
Mr Kean said that Mr Callinan told him that Sgt McCabe was a troublemaker, obstructive and difficult.
Mr Kean agreed that he had not been told anything about sexual allegations by Mr Callinan.
Mr Kean also said he did not recollect speaking to former Garda press officer Supt Taylor when he was trying to get in touch with the Garda commissioner.
Tribunal barrister Diarmaid McGuinness SC said the phone records available to the tribunal did not seem to support any contacts between Mr Kean and Supt Taylor. Mr Kean said he thought he had spoken to retired Chief Superintendent Diarmuid O'Sullivan, who suggested he contact Mr Callinan.
Mr O'Sullivan told the tribunal he did not recollect speaking to Mr Kean, but if he had been, he would have directed Mr Kean to contact the Garda press office.
Tribunal chairman Mr Justice Peter Charleton said it was "a very weird coincidence" a telephone conversation between Mr Kean and Mr O'Sullivan was followed by a phone call between Mr O'Sullivan and Mr Callinan.
Telephone records show contacts between Mr O'Sullivan and Mr Kean the Saturday before the RTE radio appearance, and on the Sunday afternoon subsequently.