A former detective sergeant has denied playing the "green card" at the Smithwick Tribunal by accusing the British authorities of conspiring to prove garda collusion with the IRA.

Owen Corrigan also said he never met Freddie Scappaticci, a man who denies being in the IRA's internal security unit known as the Nutting Squad and a top British agent at the same time.

Mr Corrigan, who was a detective sergeant in Dundalk for years, said "I wouldn't know him from Adam."

Mr Corrigan is one of three former garda sergeants being investigated by the Smithwick Tribunal to see if they passed information to the IRA, which led to the deaths of RUC Chief Supt Harry Breen and Supt Bob Buchanan.

They died in an ambush just minutes after leaving a meeting in Dundalk Garda Station in March 1989.

The witness, along with Finbarr Hickey and Leo Colton, deny the allegation.

Mr Corrigan told Justin Dillon, counsel for the Tribunal, that he could not recall what he was doing on the day the two RUC men were murdered.

Under cross examination by Neil Rafferty, counsel for former British agent Peter Keeley, the witness denied that he was involved in collusion with the IRA or that he was a smuggler or engaged in insurance fraud.

The Tribunal had earlier heard Mr Keeley claim he was in a car with IRA leader, Anthony 'Mooch' Blair when Mr Corrigan got into the car and passed information to them.

Mr Corrigan vehemently denies that ever happened and has described Mr Keeley as a "fantasist."

Mr Corrigan said the Smithwick Tribunal was set up as a result of a British conspiracy to prove there was garda collusion with the IRA.

He claims this was done to “take the heat” out of demands for investigations into the collusion in Northern Ireland.

Mr Rafferty put it to the witness that he was making all this up.

"It is the oldest trick in Irish political life, when the going gets tough to play the orange or green card.

By blaming it all on a big bad British conspiracy you're playing the green card," he said.

Mr Corrigan denied that is the case and said he was telling the truth.

The witness was also asked about Francie Tiernan, who was kidnapped along with Mr Corrigan by the IRA from a Drogheda hotel.

The former detective sergeant said he was aware Mr Tiernan was involved in smuggling and insurance scams but he was not a member of the Provisional IRA, a claim which had been made earlier by a former Garda Chief Superintendent.

Mr Corrigan's evidence resumes on Thursday.