Documents with the name of former Rehab executive and former Fine Gael advisor Frank Flannery feature in an exposé of tax havens published after a year-long investigation into 11.5 million leaked documents.

The leaked documents came from Mossack Fonseca, a law firm with offices in more than 35 countries, and were published yesterday as part of inquiry by the International Consortium of Investigative Journalists and German daily Sueddeutsche Zeitung.

Irish Times Legal Affairs Correspondent Colm Keena described the circumstances in which Mr Flannery’s name appeared in the Panama papers.

Speaking on RTÉ's Morning Ireland, Mr Keena said Mr Flannery's name appears in relation to a British Virgin Island company called 'International Funding Promotion Limited'.

The ownership of this company is not clear.

There are documents in the files showing letters coming from Bank of Ireland in London addressed to Mr Flannery and his wife in 1996, at a time they were taking out a loan to buy a house in London.

The first letter sets out the loan conditions while the second - issued on the date and by the same bank official - says, in addition to the conditions set out in the first letter, that they will be relying on an offshore deposit of £250,000.

These letters were issued in April 1996.

In May 1996 the British Virgin Island company was established.

Mr Keena said that in August 1996, after the sale of the house, the company registers the fact that it has provided this offshore account as collateral against the mortgage. 

The files contained signed versions of the first bank letter but not the second, which is the only one that refers to the British Virgin Island company.

Mr Keena said that it is not known who was behind the company. 

He added that Mr Flannery said he had bought the house 100% with a loan from Bank of Ireland in London and there were no third parties involved in the transaction. 

Mr Flannery said that he remembers the first letter but has no recollection of the second.

Mr Keena said: "It is extraordinary that you would have a senior manager in Bank of Ireland private banking apparently writing this letter."

He said that over subsequent months the bank official, Joe Holden, took measures and signed documents that appeared to follow through on the contents of the second letter.

These documents include a letter that is signed and stamped by the British Virgin Islands company and Mr Holden and is addressed to Bank of Ireland in Jersey - where the account is holding the deposit.

Mr Keena said it was an "extraordinary" story.

Oxfam chief unsurprised by scale of revelations

Oxfam chief executive Jim Clarken, meanwhile, has said he was not surprised by the scale of the revelations in the Panama Papers.

Speaking to RTÉ’s Morning Ireland, Mr Clarken said there was no doubt that Ireland has been part of this system.

He said Ireland has a vague and opaque tax system that was not serving the vast majority of citizens.

"The public will not stand for this any longer so we have to see a change. We know what this country has gone through in the last number of years,” said Mr Clarken.

"If there's a sense that money was not paid to the Irish tax authorities during the worst of our crisis and people were left on the streets to die or left on trollies and so on, it will be demanded by the public that a change happens and we have seen that this is what the public are already saying."

Minister for Jobs, Enterprise and Innovation Richard Bruton said the Government has been very active in working through the so-called BEPS process in the OECD towards arrangements that prevent aggressive management of tax to rob authorities of their tax revenue.

He said Ireland's tax policies have always been very clear and there have never been any special deals.

Speaking to RTÉ’s News at One, Mr Bruton said there are real problems where multinational companies can aggressively exploit differences in the tax codes and Ireland has been to the forefront in tackling these issues.

He said Ireland is ahead of the issue but any concerns that arise as a result of the Panama Files will have to be investigated.

He denied that Ireland could be 'a link in the chain' that facilitated people and companies in hiding money.

"I think what you saw in the past was that there were certain approaches to tax in Ireland that were different from approaches in other countries and loopholes between those were being exploited," said Mr Bruton.

"Ireland has moved ahead of all this BEPS process to close down those - the so called 'double Irish'. We have been leading the field in this regard, that once you saw this pattern of behaviour we have moved to fix it from an Irish point of view."

He said in relation to Mr Flannery he would not comment on any individual case, and if there are issues to be investigated then there are authorities to do so.