The banking inquiry is to meet today to discuss whether to pursue matter of the alleged leaking of official documents provided by a forthcoming contributor. The meeting comes after a written statement from former Department of Finance secretary general Kevin Cardiff was published in the Sunday Business Post.

Inquiry chairman Ciarán Lynch is expected to remind committee members that the leaking of documents is a criminal offence that carries a possible fine of €500,000 or imprisonment of up to five years. A spokesman for the inquiry said the issue would be discussed today but it was unknown what route members would take.

Sinn Féin TD Pearse Doherty, a committee member, said this had set a dangerous precedent and could be an attempt to undermine or interfere with the inquiry’s work.

Fianna Fáil’s public expenditure spokesman Seán Fleming, who does not sit on the committee, said it was a “very serious matter” for the members.

"We don't know the circumstances of whether it came from someone in the Oireachtas or outside of the Oireachtas. This could undermine the inquiry. I would be worried if there were an attempt by people – God knows who they may be – to undermine the banking inquiry," he said.

Mr Cardiff, the senior banking official at the department on the night of the guarantee, September 29th, 2008, is to appear before the committee on Thursday morning. He will be followed by former department secretary general John Moran and his successor, Derek Moran.

Mr Cardiff's evidence is expected to contrast sharply with testimony already given to the committee by senior bankers Eugene Sheehy, the former AIB chief executive, and Brian Goggin, the former Bank of Ireland chief executive.

Minister for Transport Paschal Donohoe said it was “a pity”

the evidence had been distributed before Mr Cardiff had had an opportunity to present it. “I think the banking inquiry has already shown what a valuable role it can play in allowing different views to emerge in relation to the causes of our crisis and allowing different figures who were involved in the run-up to the crisis to come out and give their case as to what happened,” he said.

“While the emergence of his testimony now is unfortunate, I don’t believe it will in any way derail the hearing later on this week or derail the inquiry, which has shown it can play a very valuable role in understanding the different things that led to the downfall of our banking system.”

He said he was “absolutely confident that everybody involved in the banking inquiry is playing their part in making sure that it is an impartial and valuable process”.

The committee will also discuss the proposal by Fianna Fáil finance spokesman Michael McGrath to issue an invitation to businessman Denis O'Brien to appear before the inquiry.

However, there is said to be reluctance among members to invite Mr O’Brien, considering that a commission of investigation has been established to examine the dealings of Irish Bank Resolution Corporation, which was formed in 2011 after the merger of Anglo Irish Bank and Irish Nationwide Building Society.