We fully appreciate that politicians, the media and individual citizens have a crucial role in holding the National Asset Management Agency (Nama) to account.

Nama ultimately belongs to the people of Ireland. It is right and proper that the agency is subject to rigorous scrutiny so that the people can be assured we are doing our job properly.

We accept that this scrutiny is part of the job.

But it is, perhaps, a sign of a public disenchantment that goes far beyond Nama that those who make unsubstantiated allegations about us are able to do so – and given platforms to do so – without their claims being subjected to scrutiny of any kind.

Furthermore, when we challenge those who make false claims about us, it is striking that we are asked to provide evidence to contradict the allegations, yet those who make the allegations need no evidence whatsoever.

Nama has nothing to hide, yet it appears that our critics have nothing to prove. To any objective observer, it is clear that we have reached a stage where the scrutiny of Nama’s sale of its Northern Ireland portfolio (Project Eagle) is no longer about Nama.

Last week, I joined Nama’s chief executive, Brendan McDonagh, and the senior management team in appearing before the Oireachtas Public Accounts Committee and answering its questions for about five hours. It was the second time we have done so in less than three months.

By our estimates, Nama has now answered several hundred questions on Project Eagle from the Public Accounts Committee and the Northern Ireland Finance Committee. We have answered several hundred more from media outlets in Ireland, Northern Ireland and beyond.

We have done this truthfully and professionally.

At this stage there is no additional material piece of information relevant to Project Eagle that we are aware of that Nama can put in the public domain.

Competitive sales process

The sale was conducted in line with international best practice, independently overseen by Lazard, a major international investment bank. The integrity of the sales process was fully protected.

No external members of the Northern Ireland Advisory Committee had access to confidential information on the sale.

No third parties, political or otherwise, had influence over the Nama board’s decision to sell the portfolio. None were in a position to confer an unfair competitive advantage on any bidder.

The UK National Crime Agency has made it clear to us that it is in no way concerned about Nama’s role in the sale.

Yet, in some quarters, the response to Nama demonstrating that it has nothing to hide reflects poorly on people who should know better. We have seen people clutching at every conceivable straw to allege malfeasance by Nama.

Some claim we should have got a better price, but they know there was no bidder willing to pay more.

Some claim we should have abandoned the sale process, but they know this would have made it much harder to get a return from this portfolio and that it would have threatened the sale of every other portfolio Nama has successfully brought to market since.

Some claim we should have retained the portfolio and worked it out over a period of many years, but knowing what we know about this portfolio, this would have been a costly mistake.

Some claim we should have raised red flags about the role of advisers to Pimco (the bidder we excluded from consideration) who went on to advise the successful bidder. The logic of this is that we should have accepted £1.1 billion from the runner-up bidder instead of the £1.3 billion that we achieved for the taxpayer.

Noise

No one has shown how Nama could have got more from retaining and working out a heavily distressed portfolio in a peripheral market with limited growth potential, which six of the world’s biggest investment groups did not want to bid for.

And, tellingly, no one who has made allegations about Nama’s conduct has revealed anything resembling evidence to back up their claims.

By contrast, Nama can stand over the actions it has taken; Nama can back up all it has said with concrete proof.

Politicians, media and individuals are free not to take us at our word. That is their right.

But ignoring the evidence serves no one. Falling for unsubstantiated, false claims is a very poor substitute for demanding proof. Frank Daly is chairman of the National Asset Management Agency