The Republic's Supreme Court yesterday dismissed an appeal brought by Michael McKevitt against his conviction for organising terrorist activities for the Real IRA.

McKevitt had appealed the conviction and 20-year prison sentence he received five years ago on over 30 grounds including a challenge to the credibility of the State's key witness, FBI agent David Rupert.

McKevitt (54) Beech Park, Blackrock, Co Louth, appealed against his conviction by the Special Criminal Court (SCC) in August 2003 for directing terrorist activities for the Real IRA -- becoming the first person in the State to be jailed on such a charge. He was sentenced to 20 years in jail by the SCC and he appealed his conviction to the Court of Criminal Appeal (CCA) which found the SCC judgment was safe.

He then obtained permission to have a point of law referred to the Supreme Court whose five judges yesterday unanimously agreed that the appeal should be struck out. McKevitt was not present in court for the judgment yesterday.

In his Supreme Court action, McKevitt challenged the credibility of key witness David Rupert, claiming his defence team had not been supplied with all information in relation to him (Rupert).

Mr Rupert, a New York native, claimed he infiltrated the Real IRA and attended its Army Council meetings which McKevitt also attended.

It was claimed that the SCC failed to to address Mr Rupert's involvement in criminal activity and that his agreement to become an FBI agent may have been motivated by a promise by the American authorities not to investigate him. Mr Rupert was involved in a number of criminal activities including people trafficking, drugs and money laundering, McKevitt's lawyers said.

It was also argued there was inadequate disclosure of documentary evidence relevant to Mr Rupert's credibility in the possession of authorities outside of the jurisdiction to McKevitt's lawyers.

There had also been piecemeal and late disclosure of material, including garda surveillance records, which prejudiced McKevitt's right to a fair trial, it was claimed.

The DPP argued that McKevitt headed the organisation of "mayhem throughout these islands and beyond". The central evidence of Mr Rupert relating to McKevitt had not been challenged in his trial, in the CCA or in the Supreme Court, the DPP said. Giving the judgment on behalf of the Supreme Court yesterday, Mr Justice Hugh Geoghegan held there was "abundant evidence" that the SCC was mindful fully of the potential unreliability of Mr Rupert's evidence but nevertheless believed him.

"The fact that Mr Rupert may or may not have a shady background, depending on your point of view, and the fact that as a paid agent he might be suspect as a witness at any rate are neither here nor there," the judge said.

Mr Justice Geoghegan said that the defence were provided with more than adequate material, including documents from the FBI and the British security services, about David Rupert's past, and which related to many questionable episodes in his life. Noting that substantial amount of documents had been made to the defence, Mr Justice Geoghegan added that any problems dealing with foreign agencies appeared to have been handled with great skill and fairness.

The judge also ruled that the suggestion material disclosed at a late stage rendered the trial so unfair that the conviction should be quashed was "far fetched in the extreme".