Evidence linking politicians in Northern Ireland to a massive property deal allegedly involving multi-million pound fixer fees could emerge in the coming weeks, the Dáil has heard.
Fianna Fáil leader Micheál Martin said the Government's position on the £1.2bn sale of a Northern Ireland property loan portfolio by NAMA was becoming more untenable by the day.
The deal two years ago with US investment giant Cerberus has been dogged by controversy after £7m linked to it was found in an Isle of Man bank account.
Investigations have been launched by the UK's National Crime Agency, the US Department of Justice's Securities and Exchange Commission as well as a parliamentary inquiry in Belfast.
But Taoiseach Enda Kenny has repeatedly rejected calls for a State inquiry into the so-called Project Eagle sale.
Mr Martin said the "nothing to see here" attitude was incredible.
"As revelations emerge, and as the levels of the investigations get deeper, the Government's position in relation to the sale of Project Eagle by NAMA is, in my view, more untenable by the day," he said.
"The sense that there is nothing to investigate down here or there is no necessity for the Government of the Irish Republic to be overly concerned about this particular deal - I don't think that is credible."
Mr Martin said there are huge ethical questions over the entire sale of the portfolio, which he claims resulted in substantial losses to the Irish taxpayer.
"The deal is tainted - of that there can be no question," he told the Dáil.
He added: "There seems to be a sense of a connection, of a nexus, between politics and all of this in the North as well.
"That may emerge in the coming weeks."
But Mr Kenny denied the Government was being defensive about the deal and called for evidence that a fair process was not followed.
"I'm informed that this loan sale was executed in a proper manner," he said.
"Despite all the comments and allegations there are no claims of wrongdoing against NAMA.
"That loan portfolio was sold after an open process to the highest bidder for what it was worth.
"NAMA paid no monies to any party against whom allegations of wrongdoing are being made."
Two men were arrested last month in Co Down as part of the National Crime Agency inquiry and subsequently released on bail.
NAMA sold 800 property loans to Cerberus, a multi-billion fund which boasts former US vice president Dan Quayle in its ranks.
The £7 million was paid into an account controlled by a former managing partner of Belfast-based law firm Tughans who resigned after it was unearthed.
Tughans, which was involved in the NAMA transaction as subcontractor for Cerberus's US lawyers Brown Rudnick, insisted it was not aware of the transfer.
All parties involved in the £1.2 billion transaction in 2014 have denied wrongdoing.
Sinn Féin leader Gerry Adams said a State inquiry was "definitely" needed into the affair.
