Michael Lowry is to challenge the findings of the Moriarty tribunal after the chairman, Mr Justice Michael Moriarty, issued a cost order this week denying him approximately two-thirds of his claimed legal fees.

It is understood the Tipperary TD is looking for fees totalling approximately €8 million.

The decision by the tribunal chairman not to grant the former communications minister all his costs "changes everything legally", Mr Lowry said in a statement last night in which he declared his intention to go to the High Court and to the European courts if necessary.

Up to now, Mr Lowry said, he had been advised there was no legal basis for challenging the tribunal’s findings.

However the costs decision by the tribunal now allows him to take a case.

Denis O’Brien, who along with Mr Lowry said in the wake of the tribunal’s findings that they were incorrect, has said in the past he would challenge the chairman’s report but has not yet done so. It is understood he has not yet received his response to his application for his legal costs. His spokesman could not be contacted last night.

Mr Lowry said he would be challenging all grounds for denying him legal fees. The most substantial, in terms of its effect on the amount of legal fees he is being granted, has to do with the inquiry into the mobile phone licence competition.