A retired Irish detective who said an MI5 agent was "unreliable" and "a spacer" has told the Smithwick tribunal that the man he was talking about was not Peter Keeley, the British agent also known as 'Kevin Fulton'.

Garda sergeant Tom Fox clarified his evidence from last Friday when he was shown a photograph of Mr Keeley at the tribunal.

The image, taken from a website, was supplied to the tribunal by lawyers representing Belfast republican Freddie Scappaticci.

"I can confirm to you that I never saw that man in my life," Mr Fox told the inquiry.

The ex-detective said the man he had referred to in his evidence was a Mr McCann, who he had believed was also Mr Keeley. Inquiries at the social welfare office in Dundalk after Mr McCann left the area had revealed that no person of that name was signing on, he said, although Mr McCann had been seen regularly at the office.

Mr Fox also said a man known as 'Mooch' Blair was well-known to gardai in Dundalk.

Counsel for Mr Keeley said Mr Blair was "a well-known subversive", and his client often drove Mr Blair in Dundalk.

In response to a question from counsel for retired detective sergeant Owen Corrigan, the tribunal was told that his real name was Peter Keeley, and this was the name he operated under while working as an MI5 British agent.

The tribunal heard that 'Kevin Fulton' was a pseudonym invented by a journalist when Mr Keeley gave interviews about the Omagh bombing and allegations that Mr Corrigan was an IRA "mole".

Mr Corrigan has described the allegation as a "monstrous lie".

The tribunal is examining claims of garda collusion in the deaths of RUC chief superintendent Harry Breen and superintendent Bob Buchanan as they returned from a meeting in Dundalk garda station in March 1989.

Retired assistant commissioner Edward O'Dea was sent to Dundalk in the days following the murder of the two RUC officers to investigate how the meeting was set up and who knew about it.

"I did a complete report, I sent it to the commissioner. It didn't come back to me," Mr O'Dea said.

In the report, Mr O'Dea concluded that no leak about the meeting came from within An Garda Siochana.

Mr O'Dea said that Buchanan "was really setting himself up" by travelling regularly to Garda stations in his own car without changing licence plates. And he said there was "no way" former Det Sgt Owen Corrigan would tip off the IRA. "I have no doubt in my mind as to his loyalty to the force."

The tribunal resumes in September.