Taoiseach Enda Kenny has rejected any claims that Fine Gael has been too close to businessman Denis O'Brien, saying: "I have no dealings with Denis O'Brien at all.

He also said all issues relating to IBRC will be dealt with in such a way as to "ensure public confidence".

Speaking on his arrival at a summit of EU and Latin American leaders in Brussels, Mr Kenny insisted that the Commission of Investigation into IBRC would be done "fully and professionally" and the terms of reference were there "whether it was Denis O'Brien or anybody else."

Mr Kenny said the Attorney General had confirmed that the documentation provided by Sinn Féin TD Pearse Doherty was eligible to be considered by the commission of investigation into IBRC.

He said other issues that might arise in due course could also be examined by the judge appointed head of the Commission.

The Taoiseach acknowledged there was a risk that the process could be time-consuming if further issues arose.

"The wider you make the terms of reference the more work there is to be done and it's not going to be easy work," he told reporters.

"But the Government has committed to resourcing the Commission of investigation adequately and providing the opportunity for whatever expertise is required."

He added: "Who knows what may arise in terms of other court cases, I can't speak for that."

Mr Kenny said that if the investigation took longer than the original remit of six months he would expect the head of the Commission to produce a preliminary report by the end of the year on the work done so far.

He said: "You can't politicise or dictate to a sole member what he should investigate."

When asked if Fine Gael had been too close to Mr O'Brien Mr Kenny replied: "I have no dealings with Denis O'Brien at all ... be clear on this: this Commission of Investigation is set up by the Government with terms of reference, taking into account the views and proposals of Opposition parties and members in order that the allegations and assertions, and the questions that are being asked, can be answered fully and completely and transparently.

"What happened in the past is in the past. I'm happy to lead a Government and to set out the terms of reference on behalf of the Government, with the Commission of Investigation, to do its job, so whether it's Denis O'Brien or anybody else the terms of reference are there for the Commission of Investigation and I expect that they'll do their job, fully, completely, thoroughly, adequately and very professionally, so that those concerns can be laid [to rest] properly", he said.